1.

A two-sample t-test for a difference in means was conducted to investigate whether defensive players on a football team can bench-press more weight, on average, than offensive players. The conditions for inference were met, and the test produced a test statistic of t=1.083 and a p-value of 0.15.

Based on the p-value and a significance level of �=0.05, which of the following is the correct conclusion?

a)

Reject the null hypothesis because 0.15>0.05. There is not convincing evidence that defensive players can bench-press more weight, on average, than offensive players.

b)

Reject the null hypothesis because 0.15>0.05. There is convincing evidence that defensive players can bench-press more weight, on average, than offensive players.

c)

Fail to reject the null hypothesis because 0.15>0.05. There is not convincing evidence that defensive players can bench-press more weight, on average, than offensive players.

d)

Fail to reject the null hypothesis because 0.15>0.05. There is convincing evidence that defensive players can bench-press more weight, on average, than offensive players.

e)

Fail to reject the null hypothesis because 0.15>0.05. There is convincing evidence that defensive players can bench-press the same amount of weight, on average, as offensive players.

2.

To test the durability of cell phone screens, phones are dropped from a height of 1 meter until they break. A random sample of 40 phones was selected from each of two manufacturers. The phones in the samples were dropped until the screens broke. The difference in the mean number of drops was recorded and used to construct the 90 percent confidence interval (0.46,⁢1.82) to estimate the population difference in means.

Consider the sampling procedure taking place repeatedly. Each time samples are selected, the phones are dropped and the statistics are used to construct a 90 percent confidence interval for the difference in means. Which of the following statements is a correct interpretation of the intervals?

a)

Approximately 90 percent of the intervals will extend from 0.46 to 1.82.

b)

Approximately 90 percent of the intervals constructed will capture the difference in sample means.

c)

Approximately 90 percent of the intervals constructed will capture the difference in population means.

d)

Approximately 90 percent of the intervals constructed will capture at least one of the sample means.

e)

Approximately 90 percent of the intervals constructed will capture at least one of the population means.

3.

A national consumer agency selected independent random samples of 45 owners of newer cars (less than five years old) and 40 owners of older cars (more than five years old) to estimate the difference in mean dollar cost of yearly routine maintenance, such as oil changes, tire rotations, filters, and wiper blades. The agency found the mean dollar cost per year for newer cars was $195 with a standard deviation of $46. For older cars, the mean was $286 with a standard deviation of $58.

Which of the following represents the 95 percent confidence interval to estimate the difference (newer minus older) in the mean dollar cost of routine maintenance between newer and older cars?

a)

b)

c)

d)

e)

4.

Animal researchers studying cows and horses conducted a two-sample t-test for a difference in means to investigate whether grazing cows eat more grass, on average, than grazing horses. All conditions for inference were met, and the test produced a test statistic of t=1.664 and a p-value of 0.0487.

Which of the following is a correct interpretation of the p-value?

a)

The probability that cows eat more grass than horses, on average, is 0.0487.

b)

The probability that cows eat the same amount of grass as horses, on average, is 0.0487.

c)

Assuming that the mean amount of grass eaten by cows is greater than the mean amount of grass eaten by horses, the probability of observing a test statistic of at most 1.664 is 0.0487.

d)

Assuming that the mean amount of grass eaten by cows is equal to the mean amount of grass eaten by horses, the probability of observing a test statistic of at most 1.664 is 0.0487.

e)

Assuming that the mean amount of grass eaten by cows is equal to the mean amount of grass eaten by horses, the probability of observing a test statistic of at least 1.664 is 0.0487.

5.

A study was conducted to investigate whether the mean price of a dozen eggs was different for two different grocery stores, Store A and Store B, in a large city. A carton of one dozen eggs from each store was randomly selected for each of 35 weeks, for a total sample size of 35 cartons from each store. The mean price of the 35 cartons was recorded for each store. The difference in the mean carton price for the stores will be calculated.

Which of the following is the appropriate test for the study?

a)

A one-sample t-test for a population proportion

b)

A one-sample t-test for a sample mean

c)

A matched-pairs t-test for a mean difference

d)

A two-sample t-test for a difference between population means

e)

A two-sample t-test for a difference between population proportions

6.

A two-sample t-test for a difference in means was conducted to investigate whether the average time to swim a lap with the freestyle stroke is different from the average time to swim a lap with the butterfly stroke. With all conditions for inference met, the test produced a test statistic of t=−2.073 and a p-value of 0.042.

Based on the p-value and a significance level of alpha=0.05, which of the following is a correct conclusion?

a)

There is convincing statistical evidence that the average time to swim a lap with the freestyle stroke is less than the average time to swim a lap with the butterfly stroke.

b)

There is convincing statistical evidence that the average time to swim a lap with the freestyle stroke is different from the average time to swim a lap with the butterfly stroke

c)

There is not convincing statistical evidence that the average time to swim a lap with the freestyle stroke is greater than the average time to swim a lap with the butterfly stroke.

d)

There is not convincing statistical evidence that the average time to swim a lap with the freestyle stroke is different from the average time to swim a lap with the butterfly stroke.

e)

There is not convincing statistical evidence that the average time to swim a lap with the freestyle stroke is less than the average time to swim a lap with the butterfly stroke.

7.

A biologist studied the frequency of croaks for frogs from two different regions. From a random sample of 32 frogs located in the northern region, the mean number of croaks per hour was 21.3, and from a random sample of 38 frogs located in the southern region, the mean number of croaks per hour was 28.9. To estimate the difference in the mean number of croaks (southern minus northern), a 95 percent confidence interval was constructed from the samples. The interval was reported as (7.1,8.1).

Which of the following claims is supported by the interval?

a)

All southern frogs croak more times per hour than do all northern frogs.

b)

The northern frogs are likely to have a greater mean number of croaks per hour than the southern frogs.

c)

The southern frogs are likely to have a greater mean number of croaks per hour than the northern frogs.

d)

All frogs in the study have about the same number of croaks per hour.

e)

The northern and southern frogs have the same mean number of croaks per hour.

8.

A consumer group studied two different manufacturers of cars, J and K, to investigate differences in gas mileage for cars made by the two manufacturers. For a similar type of car, a random sample of 15 cars from J and a random sample of 12 cars from K were selected, and the gas mileages, in miles per gallon (mpg), were recorded. The difference in the sample mean gas mileages was used to construct the 90 percent confidence interval (3.5,5.7).

Assuming all conditions for inference were met, which of the following is a correct interpretation of the interval?

a)

The probability is 0.90 that the difference in sample means for gas mileage for the two car manufacturers is between 3.5 mpg and 5.7 mpg.

b)

The probability is 0.90 that the population mean difference in gas mileage for the two car manufacturers is between 3.5 mpg and 5.7 mpg.

c)

About 90 percent of the differences in gas mileage for the two car manufacturers are between 3.5 mpg and 5.7 mpg.

d)

We are 90 percent confident that the difference in sample means for gas mileage for the two car manufacturers is between 3.5 mpg and 5.7 mpg.

e)

We are 90 percent confident that the population mean difference of gas mileage for the two car manufacturers is between 3.5 mpg and 5.7 mpg.

9.

A 99 percent confidence interval for a difference in means was given as 25.1±4.3.

Assuming all conditions for inference were met, which of the following is a correct interpretation of the 99 percent confidence level?

a)

In repeated samples of the same size, approximately 99 percent of the intervals constructed from the samples will extend from 20.8 to 29.4.

b)

In repeated samples of the same size, approximately 99 percent of the sample means will fall between 20.8 and 29.4.

c)

In repeated samples of the same size, approximately 99 percent of the samples will fall between 20.8 and 29.4.

d)

In repeated samples of the same size, approximately 99 percent of the intervals constructed from the samples will capture the difference in sample means.

e)

In repeated samples of the same size, approximately 99 percent of the intervals constructed from the samples will capture the difference in population means.

10.

Researchers investigated whether there is a difference between two headache medications, R and S. Researchers measured the mean times required to obtain relief from a headache for patients taking one of the medications. From a random sample of 75 people with chronic headaches, 38 were randomly assigned to medication R and the remaining 37 were assigned to medication S. The time, in minutes, until each person experienced relief from a headache was recorded. The sample mean times were calculated for each medication.

Have the conditions been met for inference with a confidence interval for the difference in population means?

a)

Yes, all conditions have been met.

b)

No, because the data were not collected using a random sample.

c)

No, because cause and effect cannot be inferred since there is a random sample.

d)

No, because the sample sizes are not large enough to assume the distribution of the difference in sample means is approximately normal.

e)

No, because the sample sizes are not the same.

11.

A two-sample t-test for a difference in means will be conducted to investigate whether the average length of a cell phone call is shorter this year compared with 5 years ago. From a random sample of 35 phone call records this year, the average length was 25 minutes with a standard deviation of 4 minutes. From a random sample of 32 phone call records from 5 years ago, the average length was 27 minutes with a standard deviation of 5 minutes. The difference (this year minus five years ago) in means will be calculated.

With a null hypothesis of no difference in length, which of the following is a correct test statistic for the test?

a)

b)

c)

d)

e)

12.

A soda manufacturer claims that its Cherry Fizz soda has more carbonation than a competitor’s Cherry Eclipse soda. Bottles of both types of soda are opened, covered with a balloon, and then shaken. The diameter of each balloon is then measured. The mean balloon diameters are 2.3 inches for the Cherry Fizz soda and 2.1 inches for the Cherry Eclipse soda. A 90 percent confidence interval to estimate the difference in mean diameters, in inches, is (−0.8,1.2). Which of the following claims is supported by the interval?

a)

Because 2.3 inches is larger than 2.1 inches, the manufacturer is correct, and Cherry Fizz has more carbonation.

b)

Because the interval has more positive values than negative values, Cherry Fizz has more carbonation.

c)

Because 2.3 and 2.1 are very similar, there is no difference in the mean carbonation levels

d)

The interval cannot be interpreted because negative measurements are not possible.

e)

Because the interval contains 0, it is possible that there is no difference in mean carbonation levels.

13.

The management of a large hardware store is interested in estimating the difference between the mean dollar amount of purchases made by customers who use the store’s credit card and the mean dollar amount of purchases made by customers who use a different credit card. A random sample of 74 customers who used the store’s credit card showed a mean purchase of $107 with a standard deviation of $12. A separate random sample of 58 customers who used a different credit card showed a mean purchase of $132 with a standard deviation of $9. Technology was used to calculate that the correct number of degrees of freedom is 129.78.

Which of the following represents the margin of error for a 98 percent confidence interval to estimate the difference in the mean purchase amount for the two types of credit cards?

a)

b)

c)

d)

e)

14.

The weekly sales at two movie theaters were recorded for a random sample of 25 weeks. A 95 percent confidence interval for the difference in mean weekly sales for the two movie theaters was calculated as ($1,288,$2,586).

With all else remaining constant, which of the following would have resulted in a confidence interval narrower than the calculated interval?

a)

A sample size less than 25

b)

A sample size greater than 25

c)

An increase to 99 percent confidence

d)

A sample mean greater than $1,937

e)

A sample mean less than $1,937

15.

Random samples of players for two types of video games were selected, and the mean number of hours per week spent playing the games was calculated for each group. The sample means were used to construct the 90 percent confidence interval (1.5,3.8) for the difference in the mean number of hours per week spent playing the games.

The maker of one of the video games claims that there is a difference in the population mean number of hours per week spent playing the two games. Is the claim supported by the interval?

a)

Yes, because 0 is not contained in the interval.

b)

Yes, because the midpoint of the interval is greater than 1.

c)

Yes, because the margin of error for the estimate is less than 1.

d)

No, because the margin of error for the estimate is greater than 1.

e)

No, because 0 is not contained in the interval.

16.

Anne claims that a store-brand fertilizer works better than homemade compost as a soil enhancement when growing tomatoes. To test her theory, she plants two tomato plants in each of five planters. One plant in each planter is grown in soil with a store-brand fertilizer and the other plant is grown in soil with homemade compost, with the choice of soil chosen at random. In three months, she will harvest and weigh the tomatoes from each plant. Which of the following is the correct confidence interval Anne should use to analyze the data?

a)

Two sample z interval for $\mu_1-\mu_2$

b)

Paired z interval for $\mu_{diff}$

c)

Two sample t interval for $\mu_1-\mu_2$

d)

Paired t interval for $\mu_{diff}$

e)

The correct interval cannot be determined without the data

17.

The weights (in pounds) of three adult males are 160, 215, and 195. What is the standard error of the mean for these data?

a)

190

b)

27.84

c)

22.73

d)

16.07

e)

13.13

18.

You want to compute a 90% confidence interval for the mean difference in height for mothers and their adult daughters using a random sample of 30 mothers who have an adult daughter. What critical value should you use for this interval?

a)

1.645

b)

1.671

c)

1.697

d)

1.699

e)

1.761

19.

In a two-sample hypothesis test with independent samples...

a)

...one sample is used to obtain an estimate, the other sample is used to test a hypothesis.

b)

...each sample is used to perform a hypothesis test and the best of the two answers is used.

c)

...a comparison is done of the same parameter in two separate populations.

d)

...a joint hypothesis test of the population mean and population variance is done.

20.

A retail company is investigating whether to use a line (X) or square (Y) barcode with its new automatic checkout system. Which of the following hypotheses compares the proportion (p) of checkout failures for each type of barcode?

a)

$H_0:\ p_X\ =\ p_Y$ $H_1:\ p_X\ \ne\ p_Y$

b)

$H_0:\ p_X=0.5,\ p_Y\ =\ 0.5$ $H_1:\ p_X\ \ne0.5,\ p_Y\ \ne0.5$

c)

$H_0:\ p_X>0.5,\ p_Y\le0.5$ $H_1:\ p_X\ \le0.5,\ p_Y\ >\ 0.5$

d)

$H_0:\ p_{X\ }>\ 0.5,\ p_Y\ >\ 0.5$ $H_1:\ p_X\ \le0.5,\ p_Y\ \le0.5$

21.

True or False:

50 heights of women from Texas and 50 heights of women from Oregon are considered matched pair (dependent) sample data sets.

a)

True

b)

False

22.

True or False:

Weights of 40 women recorded before starting a diet and 6 months after starting a diet are considered matched pair (dependent) sample sets.

a)

True

b)

False

23.

What distribution do we use when testing claims about population proportions?

a)

F

b)

z

c)

t

d)

Chi

24.

What distribution do we use when testing claims about population means?

a)

F

b)

Z

c)

t

d)

Chi

25.

Researchers claim that a blue background enhances creativity based on the average scores below. Test the claim at a 1% significance level.

a)

P = .0021

We are more creative with blue.

b)

P = 0.9979

We are more creative with blue.

c)

P = .0021

We are more creative with red.

d)

P = 0.9979

There appears to be no difference.

26.

Tatiana wonders if the same proportion of teens and adults check social media at least once per day. She wants to obtain a random sample of people from each group to test if there is a significant difference between the proportion of teens and adults that check social media at least once per day.

a)

b)

c)

d)

27.

Caroline thinks she can flip a coin so it lands showing heads more often with her right hand. She flipped a coin 40 times with each hand. She wants to test whether she gets more heads with her right hand than her left hand. (Assume all conditions have been met.)

Which of the following would be an appropriate test statistic for their test?

a)

b)

c)

d)

e)

28.

A political consultant wondered if support for a candidate was significantly different between men and women. The consultant surveyed a random sample of voters.

The consultant wants to test if these results suggest a significant difference in support between men and women. Assume that all conditions have been met.

Which of the following would be an appropriate test statistic for their test?

a)

b)

c)

d)

e)

29.

A sociologist took a random sample of 1200 drivers and found that 59 of the 610 men in the sample had received a speeding ticket, while 28 of the 590 women in the sample had received a speeding ticket.

What can the sociologist conclude?

a)

There is sufficient evidence to show that there is a difference between proportions.

b)

There is insufficient evidence to show that there is a difference between proportions.

c)

There is sufficient evidence to show that there is no difference between proportions.

d)

There is insufficient evidence to show that there is no difference between proportions.

30.

Jillian is an analyst for a ride sharing app that connects users with drivers. She wonders if drivers in Dallas are more or less likely to cancel rides than drivers in Houston. She takes a random sample of 1000 rides from Dallas and finds that 30 were cancelled. A random sample of 1000 rides from Houston shows 24 cancelled rides.

She used these results to test whether there is a difference in the proportion of cancelled rides between the two cities. The test statistic was z = 0.83 and the P-value was approximately 0.41.

At the α = 0.01 level of significance, is there sufficient evidence to conclude that the proportion of cancelled rides is different between the two cities?

a)

Yes, since the P-value is greater than 0.01.

b)

Yes, since the test statistic is greater than 0.01.

c)

No, since the P-value is greater than 0.01.

d)

No, since the test statistic is greater than 0.01.

31.

Sanjay is researching if female students are more or less likely than male students to have received extra credit at a large university. He takes a random sample of 300 students.

Sanjay used this sample to build a 95% confidence interval to estimate the difference between the proportion of females and males receiving extra credit. The resulting interval was 0.05 ± 0.07.

Based on the interval, what do we know about the corresponding P-value and conclusion at the α = 0.05 level of significance?

a)

The P-value is less than α = 0.05, and he cannot conclude that there is a difference between the proportions.

b)

The P-value is less than α = 0.05, and he should conclude that there is a difference between the proportions.

c)

The P-value is greater than α = 0.05, and he cannot conclude that there is a difference between the proportions.

d)

The P-value is greater than α = 0.05, and he should conclude that there is a difference between the proportions.

32.

A city used to require mailed payments for parking tickets. City officials piloted a system that allowed people to choose between paying by mail or paying online. They were curious if giving people both payment options would result in fewer unpaid parking tickets. To test the new system, each parking ticket one month was printed with either a "mail only" payment option or both payment options (mail and online). Officers flipped a coin to determine which message was printed on each ticket.

The results of the study produced a test statistic of z = -2.90 and P-value of approximately 0.002. Assume that all conditions for inference were met.

At the α = 0.01 level of significance, is there sufficient evidence to conclude that the proportion of unpaid tickets is lower when both payment options are offered?

a)

Yes, since the P-value is less than 0.01.

b)

Yes, since the test statistic is less than 0.01.

c)

No, since the P-value is less than 0.01.

d)

No, since the test statistic is less than 0.01.

33.

Two pain relief medicines are tested on volunteer post-operation patients, randomly assigned to one of the two brands of medicine, as to whether or not mean duration of relief are different. Data is recorded in minutes of pain relief. What is the conclusion of the appropriate hypothesis test for this experiment?

a)

P < .05 so reject Ho.

b)

P < .05 so fail to reject Ho.

c)

P > .05 so reject Ho.

d)

P > .05 so fail to reject Ho.

e)

5% significance level is inappropriate for medical decisions.

34.

What type of test?
It is thought that the average penny is older than the average quarter. The average age of a sample of 50 pennies was 8.72 years with a s = 0.73 years and the average age of 50 quarters was 6.78 years with a s = 0.99 years.

a)

2 sample z-test for mean

b)

2 sample t-test for mean

c)

matched pairs t-test

d)

2 sample z-test for proportion

35.

A random sample of 425 citizens of Naboo found that 34% support the Galactic Republic. A sample of 585 citizens of Tatooine found that 38% support the Galactic Republic. What test would you use to determine if the the proportions are different?

a)

A 2 sample z-test for mean

b)

A 2 sample t-test for mean

c)

A matched-pairs dependent sample t-test for mean

d)

A 2 - proportion z test

36.

A Keebler sales rep claims that there are more chocolate chips in their cookie than in Chips Ahoy cookies. You take a random sample of 20 Keebler cookies and find an average of 15.8 chips per cookie and a s = 3.7 chips. A random sample of 25 Chips Ahoy yields 14.2 chips per cookie and s = 4.3 chips. What is the conclusion of the test?

a)

There is enough evidence to reject the claim that there are more chips in Keeblers.

b)

There is not enough evidence to reject the claim that there are more chips in Keeblers.

c)

There is enough evidence to support the claim that there are more chips in Keeblers.

d)

There is not enough evidence to support the claim that there are more chips in Keeblers.

37.

a)

A) Ho: The mean number of days 9th grade students absent is equal to the mean number of days 12th grade students are absent.
Ha: The mean number of days 9th grade students absent is less than the mean number of days 12th grade students are absent.

b)

B) Ho: The mean number of days 12th grade students absent is less than the mean number of days 9th grade students are absent.
Ha: The mean number of days 12th grade students absent is equal to the mean number of days 9th grade students are absent.

c)

C) Ho: The mean number of days 12th grade students absent is equal to the mean number of days 9th grade students are absent.
Ha: The mean number of days 9th grade students absent is greater than the mean number of days 12th grade students are absent.

d)

D) Ho: The mean number of days 12th grade students absent is equal to the mean number of days 9th grade students are absent.
Ha: The mean number of days 12th grade students absent is less than the mean number of days 9th grade students are absent.

38.

A market researcher suspects that employees at Company A were older on average than employees at company B. They obtained a random sample of employees ages from each company. Results are shown. Which is the correct calculation for the t-statistic?

a)

b)

c)

d)

39.

A health researcher was curious if women in India lived longer on average than men in India. They obtained data from a random sample of 216 records of people in India. Results are shown. What is the P-value?

a)

0.00526

b)

-2.58

c)

2.58

d)

0.0152

40.

120 Brand X oil filters and 90 Brand Y oil filters were tested for milligrams of residue, with the following results. Find a 95% confidence interval for μY - μX.

a)

(0.96, 1.44)

b)

B) (0.92, -0.96)

c)

C) (-1.44, -0.96)

d)

D) (-1.84, -0.56)

e)

E) (0.92, 1.48)

41.

A survey was conducted to determine the difference in gasoline mileage for two types of trucks. A random sample was taken for each model of truck, and the mean gasoline mileage, in miles per gallon, was calculated. A 98% confidence interval for the difference in the mean mileage for model A trucks and the mean mileage for model B trucks, μ_{A -}μ_B was determined to be (2.6, 4.5)

a)

Based on this sample, we are 98% confident that the average mileage for model B trucks is between 2.6 and 4.5 miles per gallon higher than the average mileage for model A trucks.

b)

We know that 98% of model A trucks get mileage that is between 2.6 and 4.5 miles per gallon higher than model B trucks.

c)

Based on this sample, we are 98% confident that the average mileage for model A trucks is between 2.6 and 4.5 miles per gallon higher than the average mileage for model B trucks.

d)

We are 98% confident that a randomly selected model A truck will get mileage that is between 2.6 and 4.5 miles per gallon higher than a randomly selected model B truck.

e)

We know that 98% of all random samples done on the population of trucks will show that the average mileage for model A trucks is between 2.6 and 4.5 miles per gallon higher than the average mileage for model B trucks.

42.

A researcher was interested in comparing the salaries of female and male employees of a particular company. Independent random samples of 8 female employees (column 1) and 15 male employees (columns 2&3) yielded the following weekly salaries (in dollars). Determine a 98% confidence interval for the difference, μ₁ - μ₂ between the mean weekly salary of all female employees and the mean weekly salary of all male employees.

a)

(-$385, $164)

b)

(-$158, $382)

c)

(-$335, $111)

d)

(-$431, $208)

e)

E) (-$382, $158)

43.

A philosophy professor wants to find out whether the mean age of the men in his large lecture class is equal to the mean age of the women in his classes. After collecting data from a random sample of his students, the professor tested the hypothesis H₀: μ_M = μ_W against the alternative H_A: μ_M≠ μ_W. The P-value for the test was 0.003. Which is true?

a)

It is very unlikely that the professor would see results like these if the mean age of men was equal to the mean age of women.

b)

There is a 0.3% chance that the mean ages for the men and women are equal.

c)

There is a 99.7% chance that another sample will give these same results.

d)

There is a 0.3% chance that another sample will give these same results.

e)

There is a 0.3% chance that the mean ages for the men and women are different.

44.

A Pew Research Center poll asked independent random samples of working women and men how much they value job security. Of the 806 women, 709 said job security was very or extremely important, compared with 802 of the 944 men surveyed. Calculate a 95% confidence interval for the difference in the proportions.

a)

(-0.002, 0.062)

b)

(0.002, 0.062)

c)

(0.003, 0.056)

d)

(0.216, 0.272)

45.

Thirty five people from a random sample of 125 workers from Company A admitted to using sick leave when they weren't really ill. Seventeen employees from a random sample of 68 workers from Company B admitted that they had used sick leave when they weren't ill. Which of the following is a 95% confidence interval for the difference in the proportions?

a)

$0.03\pm\sqrt[]{\frac{\left(0.28\right)\left(0.72\right)}{125}+\frac{\left(0.25\right)\left(0.75\right)}{68}}$

b)

$0.03\pm1.96\sqrt[]{\frac{\left(0.28\right)\left(0.72\right)}{125}+\frac{\left(0.25\right)\left(0.75\right)}{68}}$

c)

$0.03\pm1.96\sqrt[]{\frac{\left(0.28\right)\left(0.72\right)}{125}-\frac{\left(0.25\right)\left(0.75\right)}{68}}$

d)

$57\pm1.96\sqrt[]{\frac{\left(0.28\right)\left(0.72\right)}{125}+\frac{\left(0.25\right)\left(0.75\right)}{68}}$

46.

At a baseball game, 42 of 65 randomly selected people own an iPod. At a rock concert occurring at the same time across town, 34 of 52 randomly selected people own an iPod. A researcher wants to test the claim that the proportion of iPad owners at the two venues is different. A 90% confidence interval for the difference in population proportions is (-0.154, 0.138). Which of the following gives the correct outcome of the claim?

a)

Because the interval includes 0, the researcher can conclude that the proportion of iPod owners at the two venues is the same

b)

Because the center of the interval is -0.008, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.

c)

Because the interval includes 0, the researcher cannot conclude that the proportion of iPod owners at the two venues is different.

d)

Because the interval includes -0.008, the researcher cannot conclude that the proportion of iPod owners at the two venues is different.

47.

When constructing a confidence interval for a difference between two population proportions, why is it important to check that the number of successes and the number of failures in each sample is at least 10?

a)

So we can generalize the results to the populations from which the samples were selected.

b)

So we can assume that the two samples are independent.

c)

So we can assume that the observations within each sample are independent.

d)

So we can assume the sampling distribution of p1-p2 is approximately Normal.

e)

So we can assume that the populations 1 and population 2 are approximately Normal.

48.

A study of road rage asked separate random samples of 596 men and 523 women about their behavior while driving. Based on their answers, each respondent was assigned a road rage score on a scale of 0 to 20. Are the conditions for performing a two-sample t test satisfied?

a)

Maybe; we have independent random samples, but we need to look at the data to check Normality.

b)

No; road rage scores in a range between 0 and 20 can’t be Normal.

c)

No; we don’t know the population standard deviations.

d)

Yes; we have two independent random samples and large sample sizes.

49.

Thirty-five people from a random sample of 125 workers from Company A admitted to using sick leave when they weren’t really ill. Seventeen employees from a random sample of 68 workers fromCompany B admitted that they had used sick leave when they weren’t ill. A 95% confidence interval forthe difference in the proportions of workers at thetwo companies who would admit to using sick leave when they weren’t ill is

a)

A

b)

B

c)

C

d)

D

50.

The power take off drive line on tractors used in agriculture is a potentially serious hazard to operators of farm equipment. The drive line is covered by a shield in new tractors, but for a variety of reasons, the shield is often missing on older tractors. Two types of shields are the bolt-on and the flip-up. It was believed that the bolt-on shield was perceived as a nuisance by the operators and deliberately removed, but the flip-up shield is easily lifted for inspection and maintenance and may be left in place. In a study initiated by the U.S. National Safety Council, random samples of older tractors with both types of shields were taken to see what proportion of shields were removed. Of 183 tractors designed to have bolt-on shields, 35 had been removed. Of the 136 tractors with flip-up shields,15 were removed. We wish to perform a test of H0: pb = pf versus Ha: pb > pf, where pb and pf are the proportions of all tractors with the bolt-on and flip-up shields removed, respectively. Which of the following is not a condition for performing the significance test?

a)

Both populations are Normally distributed.

b)

The data come from two independent samples.

c)

Both samples were chosen at random.

d)

The counts of successes and failures are large enoughto use Normal calculations.

51.

A quiz question gives random samples of n = 10 observations from each of two Normally distributed populations. Tom uses a table of t distribution critical values and 9 degrees of freedom to calculate a 95% confidence interval for the difference in the two population means. Janelle uses her calculator’s two-sample t interval with 16.87 degrees of freedom to compute the 95% confidence interval. Assume that both students calculate the intervals correctly.Which of the following is true?

a)

Tom’s confidence interval is wider.

b)

Janelle’s confidence interval is wider.

c)

Both confidence intervals are the same.

d)

There is insufficient information to determine which confidence interval is wider.

52.

A researcher wished to compare the average amount of time spent in extracurricular activities by high school students in a suburban school district with that in a school district of a large city. The researcher obtained an SRS of 60 high school students in a large suburban school district and found the mean time spent in extracurricular activities per week to be 6 hours with a standard deviation of 3 hours. The researcher also obtained an independent SRS of 40 high school students in a large city school district and found the mean time spent in extracurricular activities per week to be 5 hours with a standard deviation of 2 hours. Suppose that the researcher decides to carry out a significance test of H0: msuburban = mcity versus a two-sided alternative.

a)

A

b)

B

c)

D

d)

E

53.

The P-value for the test is 0.048. A correct conclusionis to

a)

fail to reject H0 at the a = 0.05 level. There is convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

b)

fail to reject H0 at the a = 0.05 level. There is not convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

c)

reject H0 at the a = 0.05 level. There is not convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

d)

reject H0 at the a = 0.05 level. There is convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

54.

At a baseball game, 42 of 65 randomly selected people own an iPod. At a rock concert occurring at the same time across town, 34 of 52 randomly selected people own an iPod. A researcher wants to test the claim that the proportion of iPod owners at the two venues is different. A 90% confidence interval for the difference in population proportions(game − concert) is (−0.154, 0.138). Which of the following gives the correct outcome of the researcher’s test of the claim?

a)

Because the confidence interval includes 0, the researcher can conclude that the proportion of iPod owners at the two venues is the same.

b)

Because the center of the interval is –0.008, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.

c)

Because the confidence interval includes 0, the researcher cannot conclude that the proportion of iPod owners at the two venues is different.

d)

Because the confidence interval includes more negative than positive values, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.

55.

An SRS of size 100 is taken from Population A with proportion 0.8 of successes. An independent SRS of size 400 is taken from Population B with proportion 0.5 of successes. The sampling distribution for the difference (Population A –Population B) in sample proportions has what mean and standard deviation?

a)

mean = 0.3; standard deviation = 1.3

b)

mean = 0.3; standard deviation = 0.40

c)

mean = 0.3; standard deviation = 0.047

d)

mean = 0.3; standard deviation = 0.0022

56.

How much more effective is exercise and drug treatment than drug treatment alone at reducing the rateof heart attacks among men aged 65 and older? Tofind out, researchers perform a completely randomized experiment involving 1000 healthy males inthis age group. Half of the subjects are assigned toreceive drug treatment only, while the other half are assigned to exercise regularly and to receive drug treatment. The most appropriate inference method for answering the original research question is

a)

one-sample z test for a proportion.

b)

two-sample z interval for p1 − p2.

c)

two-sample z test for p1 − p2.

d)

two-sample t interval for m1 − m2.

57.

Researchers are interested in evaluating the effectof a natural product on reducing blood pressure.This will be done by comparing the mean reductionin blood pressure of a treatment (natural product) group and a placebo group using atwo-sample t test. The researchers would like tobe able to detect whether the natural product reduces blood pressure by at least 7 points more,on average, than the placebo. If groups of size 50 are used in the experiment, a two-sample t testusing a = 0.01 will have a power of 80% to detect a 7-point difference in mean blood pressure reduction.If the researchers want to be able todetect a 5-point difference instead, then the power of the test

a)

would be less than 80%.

b)

would be greater than 80%.

c)

would still be 80%.

d)

could be either less than or greater than 80%, dependingon whether the natural product is effective.

58.

A study of road rage asked separate random samples of 596 men and 523 women about their behavior while driving. Based on their answers, each respondent was assigned a road rage score on a scale of 0 to 20. Are the conditions for performing a two-sample t test satisfied?

a)

Maybe; we have independent random samples, but we need to look at the data to check Normality.

b)

No; road rage scores in a range between 0 and 20 can’t be Normal.

c)

No; we don’t know the population standard deviations.

d)

Yes; we have two independent random samples and large sample sizes.

59.

The power take off drive line on tractors used in agriculture is a potentially serious hazard to operators of farm equipment. The drive line is covered by a shield in new tractors, but for a variety of reasons, the shield is often missing on older tractors. Two types of shields are the bolt-on and the flip-up. It was believed that the bolt-on shield was perceived as a nuisance by the operators and deliberately removed, but the flip-up shield is easily lifted for inspection and maintenance and may be left in place. In a study initiated by the U.S. National Safety Council, random samples of older tractors with both types of shields were taken to see what proportion of shields were removed. Of 183 tractors designed to have bolt-on shields, 35 had been removed. Of the 136 tractors with flip-up shields,15 were removed. We wish to perform a test of H0: pb = pf versus Ha: pb > pf, where pb and pf are the proportions of all tractors with the bolt-on and flip-up shields removed, respectively. Which of the following is not a condition for performing the significance test?

a)

Both populations are Normally distributed.

b)

The data come from two independent samples.

c)

Both samples were chosen at random.

d)

The counts of successes and failures are large enoughto use Normal calculations.

60.

A quiz question gives random samples of n = 10 observations from each of two Normally distributed populations. Tom uses a table of t distribution critical values and 9 degrees of freedom to calculate a 95% confidence interval for the difference in the two population means. Janelle uses her calculator’s two-sample t interval with 16.87 degrees of freedom to compute the 95% confidence interval. Assume that both students calculate the intervals correctly.Which of the following is true?

a)

Tom’s confidence interval is wider.

b)

Janelle’s confidence interval is wider.

c)

Both confidence intervals are the same.

d)

There is insufficient information to determine which confidence interval is wider.

61.

The P-value for the test is 0.048. A correct conclusionis to

a)

fail to reject H0 at the a = 0.05 level. There is convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

b)

fail to reject H0 at the a = 0.05 level. There is not convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

c)

reject H0 at the a = 0.05 level. There is not convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

d)

reject H0 at the a = 0.05 level. There is convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

62.

At a baseball game, 42 of 65 randomly selected people own an iPod. At a rock concert occurring at the same time across town, 34 of 52 randomly selected people own an iPod. A researcher wants to test the claim that the proportion of iPod owners at the two venues is different. A 90% confidence interval for the difference in population proportions(game − concert) is (−0.154, 0.138). Which of the following gives the correct outcome of the researcher’s test of the claim?

a)

Because the confidence interval includes 0, the researcher can conclude that the proportion of iPod owners at the two venues is the same.

b)

Because the center of the interval is –0.008, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.

c)

Because the confidence interval includes 0, the researcher cannot conclude that the proportion of iPod owners at the two venues is different.

d)

Because the confidence interval includes more negative than positive values, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.

63.

An SRS of size 100 is taken from Population A with proportion 0.8 of successes. An independent SRS of size 400 is taken from Population B with proportion 0.5 of successes. The sampling distribution for the difference (Population A –Population B) in sample proportions has what mean and standard deviation?

a)

mean = 0.3; standard deviation = 1.3

b)

mean = 0.3; standard deviation = 0.40

c)

mean = 0.3; standard deviation = 0.047

d)

mean = 0.3; standard deviation = 0.0022

64.

How much more effective is exercise and drug treatment than drug treatment alone at reducing the rateof heart attacks among men aged 65 and older? Tofind out, researchers perform a completely randomized experiment involving 1000 healthy males inthis age group. Half of the subjects are assigned toreceive drug treatment only, while the other half are assigned to exercise regularly and to receive drug treatment. The most appropriate inference method for answering the original research question is

a)

one-sample z test for a proportion.

b)

two-sample z interval for p1 − p2.

c)

two-sample z test for p1 − p2.

d)

two-sample t interval for m1 − m2.

65.

Researchers are interested in evaluating the effectof a natural product on reducing blood pressure.This will be done by comparing the mean reductionin blood pressure of a treatment (natural product) group and a placebo group using atwo-sample t test. The researchers would like tobe able to detect whether the natural product reduces blood pressure by at least 7 points more,on average, than the placebo. If groups of size 50 are used in the experiment, a two-sample t testusing a = 0.01 will have a power of 80% to detect a 7-point difference in mean blood pressure reduction.If the researchers want to be able todetect a 5-point difference instead, then the power of the test

a)

would be less than 80%.

b)

would be greater than 80%.

c)

would still be 80%.

d)

could be either less than or greater than 80%, dependingon whether the natural product is effective.

66.

In a simple random sample of 100 households in 2000, 43 had some credit card debt. In another simple random sample of 150 households in 2012, 72 had some credit card debt. Which of the following is the correct test statistic for testing the hypothesis , that there is no difference in the proportion of households with credit card debt in these two years?

a)

A

b)

B

c)

C

67.

Choose the correct response

a)

Gives z = 2.25, P < 0.02

b)

Gives z = 2.60, P < 0.005

c)

Gives z = 2.25, P < 0.04

d)

Should not be used because the Normal Condition is violated

68.

Choose the correct response

a)

A

b)

B

c)

C

d)

D

69.

Choose the correct response

a)

A

b)

B

c)

C

d)

D

70.

A 95% confidence interval for p(m) - p(f) would be:

a)

0.06 ± 0.00095

b)

0.06 ± 0.043

c)

-0.06 ± 0.00095

d)

-0.06 ± 0.043

71.

Choose the correct response

a)

A

b)

B

c)

D

d)

E

72.

Experiments on learning in animals sometimes measure how long it takes mice to find their way through a maze. The mean time is 18 seconds for one particular maze. A researcher thinks that a loud noise will cause the mice to complete the maze faster. She measures how long each of 10 mice takes with a noise as a stimulus. The sample mean is x = 16.5 seconds. What is the alternative hypothesis for the test of significance?

a)

$H_0:\ \mu\ =18\ vs.\ H_A\ :\ \mu\ \ne18$

b)

$H_0:\ \mu\ =18\ vs.\ H_A\ :\ \mu\ <18$

c)

$H_0:\ \mu\ =18\ vs.\ H_A\ :\ \mu\ >18$

d)

$H_0:\ \mu\ <18\ vs.\ H_A\ :\ \mu\ =18$

e)

$H_0:\ \mu\ \ne18\ vs.\ H_A\ :\ \mu\ =18$

73.

You are thinking of conducting a one-sample t-test about a population mean $\mu$ using a 0.05 significance level. Which of the following statements is correct?

a)

You should not carry out the test if the sample does not have a Normal distribution

b)

You can safely carry out the test if there are no outliers, regardless of the sample size

c)

You can carry out the test if a graph of the data shows no strong skewness, regardless of the sample size.

d)

You can carry out the test only if the population standard deviation is known

e)

You can safely carry out the test if your sample size is at least 30

74.

A 95% confidence interval for μ based on n=15 observations from a normal population is ( -0.73, 1.92 ) If we use this confidence interval to test the hypothesis $H_0\ :\ \mu=0\ vs.\ H_A\ :\ \mu\ne0$ , which of the following is the most appropriate conclusion?

a)

Reject $H_0$ at the $\alpha\ =\ 0.05$ level of significance

b)

Fail to Reject $H_0$ at the $\alpha\ =\ 0.05$ level of significance

c)

Reject $H_0$ at the $\alpha\ =\ 0.10$ level of significance

d)

Fail to Reject $H_0$ at the $\alpha\ =\ 0.10$ level of significance

e)

We cannot perform the required test since we do not know the value

75.

Which of the following has the smallest probability

a)

$P\left(t>2\right)\ if\ t\ has\ 5\ df$

b)

$P\left(t>2\right)\ if\ t\ has\ 2\ df\$

c)

$P\left(z>2\right)\ \$

d)

$P\left(t<2\right)\ if\ t\ has\ 5\ df\$

e)

$P\left(t<2\right)\ if\ t\ has\ 2\ df\$

76.

A study of road rage asked random samples of 596 men and 523 women about their behavior while driving. Based on their answers, each person was assigned a road rage score on a scale of 0 to 20. Are the conditions for performing a two-sample t-test satisfied?

a)

Maybe, we have independent random samples, but we should look at the data to check Normality.

b)

No, road rage scores on a scale from 0 to 20 can't be Normal

c)

No, we don't know the population standard deviations.

d)

Yes, the large sample sizes guarantee that the corresponding population distribution will be Normal.

e)

Yes, we have tow independent random sample and large sample size.

77.

A significance test was performed to test $H_0:\ \mu=2\ vs.\ H_A:\ \mu\ne2.$ A sample of size 28 produced a standardized test statistic of t =2.051. Assuming all conditions for inference were met, which of the following intervals contains the P-value for this test?

a)

0.01 < P < 0.02

b)

0.02 < P < 0.025

c)

0.025 < P < 0.05

d)

0.05 < P < 0.10

e)

P > 0.10

78.

A government statistician claims that the mean income level of families living in subsidized housing is $9,250 with a standard deviation of $2,575. A reporter plans to test this claim through interviews with a random sample of 50 families. If she finds a sample mean more than $500 different from the claimed $9,250, she will dispute the statistician's claim. What is the probability that the reporter will mistakenly reject a true claim?

a)

0.043

b)

0.085

c)

0.170

d)

0.830

e)

0.915

79.

A guidance counselor is interested in comparing GPAs of students with home access to the Internet with students who do not have this access. She pulls the files of an SRS of ten students who do have home access to the Internet and an SRS of ten who do not, and proceeds to run a t-test to compare the mean GPAs of each group. Which of the following is a necessary assumption?

a)

The population standard deviations from each group are known.

b)

The population standard deviations from each group are equal.

c)

The samples must be independent samples, and for each sample np and n(1 - p) must both be at least 10.

d)

The population standard deviations from each group are unknown.

e)

The population of GPA scores from each group is normally distributed.

80.

A researcher wished to compare the average amount of time spent in extracurricular activities by high school students in a suburban school district with that in a school district of a large city. The researcher obtained an SRS of 60 high school students in a large suburban school district and found the mean time spent in extracurricular activities per week to be 6 hours with a standard deviation of 3 hours. The researcher also obtained an independent SRS of 40 high school students in a large city school district and found the mean time spent in extracurricular activities per week to be 5 hours with a standard deviation of 2 hours. Suppose that the researcher decides to carry out a significance test of

$H_{0\ }:\ \mu_{suburban}=\mu_{city\ }\ vs\ a\ two-sided\ alternative$

Which is the correct standardized test statistic?

a)

$z=\frac{\left(6-5\right)-0}{\sqrt[]{\left(\frac{3}{60}+\frac{2}{40}\right)}}$

b)

$z=\frac{\left(6-5\right)-0}{\sqrt[]{\left(\frac{3^2}{60}+\frac{2^2}{40}\right)}}$

c)

$z=\frac{\left(6-5\right)-0}{\frac{3}{\sqrt[]{60}}+\frac{2}{\sqrt[]{40}}}$

d)

$t=\frac{\left(6-5\right)-0}{\sqrt[]{\left(\frac{3^{ }}{60}+\frac{2^{ }}{40}\right)}}$

e)

$t=\frac{\left(6-5\right)-0}{\sqrt[]{\left(\frac{3^2}{60}+\frac{2^2}{40}\right)}}$

81.

A researcher wished to compare the average amount of time spent in extracurricular activities by high school students in a suburban school district with that in a school district of a large city. The researcher obtained an SRS of 60 high school students in a large suburban school district and found the mean time spent in extracurricular activities per week to be 6 hours with a standard deviation of 3 hours. The researcher also obtained an independent SRS of 40 high school students in a large city school district and found the mean time spent in extracurricular activities per week to be 5 hours with a standard deviation of 2 hours. Suppose that the researcher decides to carry out a significance test of

$H_{0\ }:\ \mu_{suburban}=\mu_{city\ }\ vs\ a\ two-sided\ alternative$

The P-value for the test is 0.048. A correct conclusion is to

a)

Fail to reject Ho since 0.048 < 0.05 There is convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

b)

Fail to reject Ho since 0.048 < 0.05 There is not convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

c)

Fail to reject Ho since 0.048 < 0.05 There is convincing evidence that average time spent on extracurricular activities by students in the suburban and city school districts is the same.

d)

Reject Ho since 0.048 < 0.05 There is not convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

e)

Reject Ho since 0.048 < 0.05 There is convincing evidence of a difference in the average time spent on extracurricular activities by students in the suburban and city school districts.

82.

The weighs (in pounds) of three adult males are 160, 215, and 195. What is the standard error of the mean for these data?

a)

190

b)

27.84

c)

22.73

d)

16.07

e)

13.13

83.

Are TV commercials louder than their surrounding programs? To find out, researchers collected data on 50 randomly selected commercials in a given week. With the television's volume at a fixed setting, they measured the maximum loudness of each commercial and the maximum loudness in the first 30 seconds of regular programming that followed. Assuming the conditions for inference are met, the most appropriate method for answering the question of interest is

a)

a two-sample t-test for a difference in means.

b)

a two-sample t-interval for difference in means.

c)

a paired t-test for a mean difference.

d)

a two-sample z-test for a difference in proportions.

e)

a paired t-interval for mean difference.

84.

Researchers are interested in evaluating the effect of a natural product on reducing blood pressure. They plan to carry out a randomized experiment to compare the mean reduction in blood pressure of a treatment (natural product) group and a placebo group. Then they will use the data to perform a test of

$H_0:\ \mu_T-\mu_P\ =\ 0\ vs\ H_0:\ \mu_T-\mu_P\ >\ 0$

where $\mu_T$ = the true mean reduction in blood pressure when taking the natural product and $\mu_P$ = the true mean reduction in blood pressure when taking a placebo product for subjects like the ones in the experiment. The researcher would like to detect whether the natural product reduces blood pressure by at least 7 points more, on average, than the placebo. If groups of size 50 are used in the experiment, a two-sample t-test using α=0.01 will have a power of 80% to detect a 7-point difference in mean blood pressure reduction. If the researchers want to be able to detect a 5-point difference instead, then the power of the test

a)

would be less than 80%.

b)

would be greater than 80%

c)

would still be 80%

d)

could be either less than or greater than 80%

e)

would vary depending on the standard deviation of the data.

85.

A quiz question gives random samples of n = 10 observations from each of two Normally distributed populations. Tom uses a table of t distribution critical values and 9 degrees of freedom to calculate a 95% confidence interval for the difference in the two population means. Janelle uses her calculator’s two-sample t interval with 16.87 degrees of freedom to compute the 95% confidence interval. Assume that both students calculate the intervals correctly. Which of the following is true?

a)

Tom's confidence interval is wider

b)

Janelle's Confidence interval is wider

c)

Both confidence interval are the same width

d)

There is insufficient information to determine which confidence interval is wider.

e)

Janelle made a mistake; degrees of freedom has to be a whole number.

86.

Anne claims that a store-brand fertilizer works better than homemade compost as a soil enhancement when growing tomatoes. To test her theory, she plants two tomato plants in each of five planters. One plant in each planter is grown in soil with store-brand fertilizer and the other plant is grown in soil with homemade compost, with the choice of soil determined at random. In three months, she will harvest and weigh the tomatoes from each plant. Which of the following is the correct confidence interval Anne should use to analyze these data?

a)

Two sample z interval for $\mu_1-\mu_2$

b)

Paired z interval for $\mu_{diff}$

c)

Two sample t-interval for $\mu_1-\mu_2$

d)

Paired t interval for $\mu_{diff}$

e)

The correct interval cannot be determined without the data.

87.

You want to compute a 90% confidence interval for the mean difference in height for mothers and their adult daughters using a random sample of 30 mothers who have an adult daughter. What critical value should you use for this interval?

a)

1.645

b)

1.671

c)

1.697

d)

1.699

e)

1.761

88.

We want to construct a one-sample t-interval for a population mean using data from a population with an unknown shape. In which of the following circumstances would it be inappropriate to construct the interval based on an SRS of size 14 from the population?

a)

A stem-plot of the data is roughly bell shaped.

b)

A histogram of the data shows slight skewness.

c)

A box-plot shows that the values above the median are much more variable than the values below the median.

d)

The sample standard deviation is large.

e)

The sample standard deviation is small.

89.

A 90% confidence interval for the mean $\mu$ of a population is computed from a random sample and is found to be $90\pm30$ . Which of the following could be the 95% confidence interval based on the same data?

a)

$90\pm21$

b)

$90\pm30$

c)

$90\pm39$

d)

$90\pm70$

e)

without knowing the sample size, any of the above answer could be the 95% confidence interval

90.

Do high school seniors with part-time jobs spend less time doing homework per week, on average, than seniors without part-time jobs? For a random sample of 45 seniors with part-time jobs, the mean amount of homework time is 4.2 hours with a standard deviation of 3.8 hours. For a random sample of 45 seniors without part time jobs, the mean amount of homework time is 5.8 hours with a standard deviation of 4.9 hours. Assuming the conditions are met, which of the following is the correct standard error for a 95% confidence interval for a difference in the population means?

a)

$\sqrt[]{\frac{4.9^2}{45}-\frac{3.8^2}{45}}$

b)

$\sqrt[]{\frac{4.9^2}{45}+\frac{3.8^2}{45}}$

c)

$\frac{\left(4.9-3.8\right)}{\sqrt[]{45}}$

d)

$\sqrt[]{\frac{5.8^2}{45}-\frac{4.2^2}{45}}$

e)

$\sqrt[]{\frac{5.8^2}{45}+\frac{3.8^2}{45}}$

91.

Few people enjoy melted ice cream. Being from the sunny state of Arizona, Megan and Jenna decided to test if generic vanilla ice cream melts faster than Breyers vanilla ice cream. At 10 different times during the day and night, the girls put a single scoop of each type of ice cream in the same location outside and timed how long it took for each scoop to melt completely. When constructing a paired t interval for a mean difference using these data, which of the following distributions should Megan and Jenna check for Normality?

I. The distribution of melt time for the generic ice cream

II. The distribution of melt time for the Breyers ice cream

III. The distribution of difference in melt time

a)

I only

b)

II only

c)

III only

d)

I and II

e)

I, II, and III

92.

A medical assistant sampled the blood pressures of 20 randomly selected patients with high blood pressure before and after they receive a dose of a new medicine. Which hypothesis test should she run?

a)

Paired t-test. Since the patients are the same in both sample 1 and sample 2, the two samples are linked.

b)

2-sample t-test. Since the blood pressures were taken for 20 patients in sample 1 and the same 20 patients in sample 2, use a two-sample t-test to see if the results are statistically significant.

c)

1-sample t-test. The medical assistant should compare the mean of the first sample of 20 patients to the mean of the second sample of 20 patients.

d)

2-sample t-test. There is no natural pairing between the two samples.

93.

A researcher gave one group of people an active drug and gave a different group of people an inactive placebo, then compare the blood pressures between the groups. Which test should he run to determine the efficacy of the active drug?

a)

Paired t-test. Since there is a group with the active drug and another with the inactive drug, he may pair the two two groups if the sample sizes are the same.

b)

2-sample t-test. Since the blood pressures were taken for patients in sample 1 and different patients in sample 2, use a two-sample t-test to see if the results are statistically significant.

c)

1-sample t-test. The researcher should compare the mean of the first sample of patients to the mean of the second sample of patients.

d)

2-sample z-test. There is no natural pairing between the two samples, so the researcher must use a proportions test.

94.

Is the mean height of female college students greater than 5.5 feet?

a)

Paired t-test. Students heights can be measured against females of similar backgrounds.

b)

1-sample t-test. Test whether the mean of a single sample is equal to the target value of 5.5 feet.

c)

2-sample t-test. Test whether the heights of female college students is higher than their high school heights.

d)

Use a z-test by finding the mean height and standard deviation of the sample of college females' heights.

95.

Does the mean height of female college students significantly differ from the mean height of male college students?

a)

Paired t-test. Test whether the difference of the means of one male paired with one female is equal to 0.

b)

2-sample t-test. Test whether the mean height of female college students is different than the mean height of male college students.

c)

1-sample t-test. Test whether the mean of randomly assigned pairs of female and male students is greater than the mean of the average of males and females.

d)

z-test. Use proportions in place of means to run a one sample z-test for males and females and compare averages.

96.

If you measure the weight of male college students before and after each subject takes a weight-loss pill, is the mean weight loss significant enough to conclude that the pill works?

a)

Paired t-test. Test whether the mean of the differences in weights between the male college students before they took the weight-loss pill and after they take the weight loss is significant to conclude the pill works.

b)

1-sample t-test. Test if the mean weight of the males before the study is different from the mean of the males weight after the weight-loss pill was taken.

c)

2-sample t-test. Compare the mean weights of the males both before and then after the weight-loss pill is taken to see if there is a decrease in weight between the groups overall.

d)

z-test. This is a proportion and should be tested using a one-sample z-test.

97.

The fire department of a small city wants to know if the proportion of homes having at least one smoke detector is still 90%. They take a sample of 100 homes and check if they have working smoke detectors.

a)

Paired t-test. The homes surveyed can be compared with the 90% and determined if the difference in the homes with smoke detectors now is equal to zero.

b)

1-sample t-test. This is a single sample of the mean estimated number of homes having smoke detectors.

c)

2-sample t-test. Since the population value before was 90%, compare this to the current population and determine if the difference is 0 between before and now.

d)

1-sample z-test. Since this is a proportion so we should use a z-test to see if the homes sampled still equal the current rate of 90% in this city.

98.

I run a paired t-test for 15 sets of first grade twins reading abilities if one twin used a computer program tutor and the other did not, and get a p-value of 0.02, what does this mean for a significance level of 0.05?

a)

Reject the null hypothesis. There is evidence at the 0.05 level that the computer program tutor is more effective at raising reading scores.

b)

Fail to reject the null hypothesis. There is no evidence at the 0.05 level that the computer program tutor is more effective at raising reading scores.

c)

Accept the null hypothesis. There is evidence at the 0.05 level that the computer program tutor is more effective at raising reading scores.

d)

This was not the proper use of a paired t-test; no conclusions can be drawn from this test.

99.

We use a paired t-test for 18 students in the Bethel AP statistics class and 18 students in the Kecoughtan class to see if one teacher has higher scores on the AP exam than another.We get a p-value of 0.14. What should we conclude?

a)

Reject the null hypothesis. There is evidence at the 0.05 level that the one teacher has higher scores than another.

b)

Fail to reject the null hypothesis. There is no evidence at the 0.05 level that one teacher has higher scores than another.

c)

Accept the null hypothesis. There is evidence at the 0.05 level that one teacher's scores are higher than the other teacher's.

d)

This was not the proper use of a paired t-test; no conclusions can be drawn from this test.

100.

A manufacturer of gloves wants to determine if a special type of wool gloves lasts longer than the cotton gloves they manufacture. He makes pairs of gloves in which the left hand is cotton and the right hand is wool. We sample 24 women who wear these pairs of gloves, then use a paired t-test to find the mean of the differences in wear between the right glove and left glove; we get a p-value of 0.043. At the 0.05 level, what should we conclude?

a)

Reject the null. There is evidence at the 0.05 significance level that the wool gloves lasts longer than the cotton glove.

b)

Fail to reject the null. There is evidence at the 0.05 significance level that the wool glove lasts longer than the cotton glove.

c)

Fail to reject the null. There is no evidence at the 0.05 significance level that the wool glove lasts longer than the cotton glove.

d)

We cannot conclude anything because a paired t-test was not the appropriate test to run for this sample.

101.

A random sample of 85 sixth-graders in a large city take a course designed to improve scores on a reading comprehension test. Based on this sample, a 90% confidence interval for the mean improvement in test scores for all sixth-graders in the city taking this course is found to be (12.6, 14.8). Which of the following are the sample mean and margin of error on which this interval is based?

a)

Sample Mean = 13.7; Margin of Error = 1.1

b)

Sample mean = 13.7; Margin of Error = 2.2

c)

Sample mean is unknown; Margin of Error = 1.1

d)

Sample mean is unknown; Margin of Error = 2.2

102.

A random sample of 85 sixth-graders in a large city take a course designed to improve scores on a reading comprehension test. Based on this sample, a 90% confidence interval for the mean improvement μ in test scores for all sixth-graders in the city taking this course is found to be (12.6, 14.8). Which one of the following is a correct interpretation of this confidence interval?

a)

Ninety percent of the 85 sixth-graders taking this course in the sample improved their reading comprehension scores by 12.6 to 14.8 points.

b)

The probability is 0.90 that the true mean improvement in reading comprehension for sixth-graders taking this course is between 12.6 and 14.8 points.

c)

We are 90% confident that the true improvement in reading comprehension scores of all sixth-graders taking this course is between 12.6 and 14.8 points.

d)

We are 90% confident that the true improvement in reading comprehension scores of these 85 sixth-graders is between 12.6 and 14.8 points.

103.

Agricultural researchers plant 100 plots with a new variety of corn and measure the mean yield for these plots in bushels per acre. They treat the 100 plots as a simple random sample of possible plots of corn (as researchers often do) and report a 95% confidence interval for the mean corn yield of (128.4, 131.6) bushels per acre. Which of the following is a correct interpretation of the 95% confidence level?

a)

We are 95% confident that the true mean yield for this new variety of corn is captured by the interval (128.4, 131.6) bushels per acre.

b)

If many intervals were constructed this way from many independent sets of 100 plots, 95% of the intervals would capture the true mean corn yield.

c)

If many intervals were constructed this way from many independent sets of 100 plots, 95% of the time the true mean corn yield would be in the interval (128.4, 131.6) bushels per acre.

104.

Simple random samples are taken from two large populations, designated Population 1 and Population 2. Which of the following describes a situation in which the conditions for performing a two-sample t-test for the difference of two means for these populations have NOT been satisfied?

a)

n₁ = 15, n₂ = 100. The distribution of Sample 1 is symmetric and bell-shaped with no outliers, and the distribution of Sample 2 is skewed left with a small outlier.

b)

n₁ = 15, n₂ = 15. The distributions of both samples are symmetric and bell-shaped with no outliers.

c)

n₁ = 15, n₂ = 15. The distribution of Sample 1 is symmetric and bell-shaped with no outliers, and the distribution of Sample 2 is skewed left with a small outlier.

105.

A sports physiologist wishes to compare the effects of two stepping heights (low and high) on heart rate in a step-aerobics workout. A sample of 50 adults in roughly similar physical condition was randomly divided into two groups of 25 subjects each. Group 1 did a standard step-aerobics workout using the low stepping height. The sample mean heart rate at the end of Group 1's workout was 90 beats per minute (bpm), with a sample standard deviation of 9 bpm. Group 2 did the same workout but used the high stepping height. The sample mean heart rate at the end of Group 2's workout was 95.1 bpm, with a sample standard deviation of 12 bpm. Assume that conditions for inference have been met. Let μ₁and μ₂ represent the mean heart rates we would observe for the entire population of interest if all members of the population did the workout using the low and high stepping height, respectively. Suppose that the researcher wishes to test the hypotheses H₀: μ₁ - μ₂ = 0 versus H_a : μ₁ - μ₂< 0. Which of the following is a correct expression for calculating the test statistic for this test?

a)

b)

c)

106.

A study reports that 75 percent of young adults in a county get their news from online sources. A sociologist

believes that the percentage is actually greater than 75 percent. The sociologist will select a random sample of young adults from around the county to interview. Which of the following is the most appropriate method for investigating the sociologist’s belief?

a)

A one-sample z-test for a difference in population proportions

b)

A one-sample z-ztest for a sample proportion

c)

A one-sample -z test for a population proportion

d)

A two-sample -z test for a difference in population proportions

e)

A two-sample -z test for a difference in sample proportions

107.

A random sample of 100 people from Country S had 15 people with blue eyes. A separate random sample of 100

people from Country B had 25 people with blue eyes. Assuming all conditions are met, which of the following is a

95 percent confidence interval to estimate the difference in population proportions of people with blue eyes

(Country S minus Country B) ?

a)

(-0.01, 0.21)

b)

(-0.15,-0.05)

c)

(-0.19,-0.01)

d)

(-0.21, 0.01)

e)

(-0.24,0.04)

108.

A wildlife biologist is doing research on chronic wasting disease and its impact on the deer populations in Colorado. To estimate the difference between the proportions of deer with chronic wasting disease in two different

regions, a random sample of 200 deer was obtained from one region and a random sample of 197 deer was obtained

from the other region. The biologist checked for the following (see pic). Which of the following conditions for inference was the biologist checking?

a)

The population of deer within each region is approximately normal.

b)

It is reasonable to generalize from the samples to the populations.

c)

The samples are independent of each other.

d)

The observations within each sample are close to independent.

e)

The sampling distribution of the difference in sample proportions is approximately normal.

109.

A random sample of 240 adults over the age of 40 found that 144 would use an online dating service. Another

random sample of 234 adults age 40 and under showed that 131 would use an online dating service. Assuming all

conditions are met, which of the following is the standard error for a 90 percent confidence interval to estimate the

difference between the population proportions of adults within each age group who would use an online dating

service?

a)

$\sqrt[]{\frac{\frac{144}{240}\left(1-\frac{144}{240}\right)}{240}+\frac{\frac{131}{234}\left(1-\frac{131}{234}\right)}{234}}$

b)

$1.65\sqrt[]{\frac{\frac{144}{240}\left(1-\frac{144}{240}\right)}{240}+\frac{\frac{131}{234}\left(1-\frac{131}{234}\right)}{234}}$

c)

$1.96\sqrt[]{\frac{\frac{144}{240}\left(1-\frac{144}{240}\right)}{240}+\frac{\frac{131}{234}\left(1-\frac{131}{234}\right)}{234}}$

d)

$\sqrt[]{\frac{\frac{275}{474}\left(1-\frac{275}{474}\right)}{474}}$

e)

$1.65\sqrt[]{\frac{\frac{275}{474}\left(1-\frac{275}{474}\right)}{474}}$

110.

A marketing executive is investigating whether this year’s advertising campaign has resulted in greater mean sales

compared with last year’s mean sales. The executive collects a random sample of 100 customer orders from a large

population of orders and calculates the sample mean and sample standard deviation. Which of the following is the appropriate test for the executive’s investigation?

a)

A one-sample z-test for a population mean

b)

A one-sample t-test for a population mean

c)

A one-sample z-test for a population proportion

d)

A two-sample t-test for a difference between means

e)

A matched-pairs t-test for a mean difference

111.

A report on a certain fast food restaurant states that, the mean order total, is $9. The manager of the restaurant

believes the mean is higher. A random sample of orders will be selected. The sample mean will be calculated and

used in a hypothesis test to investigate the belief. Which of the following is the correct set of hypotheses?

a)

$H_0:\ \overline{x}=9,\ H_a:\ \overline{x}\ne9$

b)

$H_0:\ \overline{x}=9,\ H_a:\ \overline{x}>9$

c)

$H_0:\ \mu=9,\ H_a:\ \mu\ne9$

d)

$H_0:\ \mu=9,\ H_a:\ \mu>9$

e)

$H_0:\ \mu=9,\ H_a:\ \mu<9$

112.

White blood cell counts are normally distributed with mean 7500 and variance 500. If a patient has taken 50 laboratory blood tests that have a mean of 6899.75 and a standard deviation of 393.44, does this give evidence that his white blood cell count is significantly different than normal?

a)

One-Sample T Test for a Mean

b)

One-Sample Z Test for a Proportion

c)

One-Sample Z Test for a Mean

d)

One-Sample T Test for a Proportion

113.

Which two factors provide evidence to state that the sampling distribution of X-bar is approximately normal?

a)

$np\ge10\ and\ n\left(1-p\right)\ge10$

b)

the population is stated as approximately normal

c)

n is greater than or equal to 30

d)

the population is stated as symmetric

114.

A medical researcher wishes to investigate the effectiveness of exercise versus diet in losing weight. Two groups of 25 overweight adult subjects are used, with a subject in each group matched to a similar subject in the other group on the basis of a number of physiological variables. One of the groups is placed on a regular program of vigorous exercise but with no restriction on diet, and the other is placed on a strict diet but with no requirement to exercise. The weight losses after 20 weeks are determined for each subject, and the difference between matched pairs of subjects (weight loss of subject in exercise group - weight loss of matched subject in diet group) is computed. The mean of these differences in weight loss is found to be 2 lb with standard deviation sₓ = 4 lb. Is this convincing evidence of a difference in mean weight loss for the two methods? To answer this question, you should use

a)

2 sample t test for μₓ

b)

one-sample z interval for μₓ

c)

one-proportion z interval

d)

paired t test for μₓ

115.

What test would be appropriate if we wanted to show evidence for the difference in average ages at which teachers and plumbers retire?

a)

Matched Pairs t-test

b)

2-Sample t-test

116.

A random sample of upperclassmen at your school is taken. What test would be appropriate if we wanted to show evidence to compare the average number of hours of sleep of juniors and seniors.

a)

Matched Pairs T

b)

2-Sample T

117.

Livestock are given a special feed supplement to see if it will promote weight gain. Researchers report that the 77 cows randomly selected for the study gained an average of 56 pounds. It is known that the regular feed promotes a weight gain of 52 pounds with a population standard deviation is 5.3 pounds. What test would you use to determine if the weight gain using the new special feed supplement is significantly higher?

a)

1 sample z test for means

b)

1 sample t test for means

c)

1 sample z test for proportions

d)

1 sample t test for proportions

118.

A study of road rage asked independent random samples of 596 men and 523 women about their behavior while driving. Based on their answers, each respondent was assigned a road rage score on a scale of 0 to 20. Are the conditions for performing a two-sample t test satisfied?

a)

Maybe; we have independent random samples, but we need to look at the data to check Normality.

b)

No; road rage scores in a range between 0 and 20 can’t be Normal.

c)

No; we don’t know the population standard deviations.

d)

Yes; we have two independent random samples, large sample sizes and the 10% condition is met.

119.

At a baseball game, 42 of 65 randomly selected people own an iPad. At a rock concert occurring at the same time across town, 34 of 52 randomly selected people own an iPad. A researcher wants to test the claim that the proportion of iPad owners at the two venues is different. A 90% confidence interval for the difference in population proportions(game − concert) is (−0.154, 0.138). Which of the following gives the correct outcome of the researcher’s test of the claim?

a)

Because the confidence interval includes 0, the researcher can conclude that the proportion of iPod owners at the two venues is the same.

b)

Because the center of the interval is –0.008, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.

c)

Because the confidence interval includes 0, the researcher cannot conclude that the proportion of iPod owners at the two venues is different.

d)

Because the confidence interval includes more negative than positive values, the researcher can conclude that a higher proportion of people at the rock concert own iPods than at the baseball game.

120.

The manager of a sporting goods store offered a bonus commission to his salespeople when they sold more goods. A new manager dropped the bonus system. For a random sample of six sales, the weeks sales (in thousands of dollars) were 3.7 with the bonus (SD of 0.15) and 3.3 without the bonus (SD of 0.21). What test would you use to determine if sales dropped when the bonus system was discontinued?

a)

1 sample t-test

b)

2 sample t-test

c)

1 proportion z-test

d)

2 proportion z-test

121.

A box of Raspberry Crunch cereal contains a mean of 13 ounces with a known standard deviation of 0.5 ounces. The distribution of the contents of cereal boxes is approximately Normal. The cereal company is afraid the boxes being over filled. Suppose they get a random sample of 25 boxes, and find a mean of 13.2 and a standard deviation of 0.154. What test would determine if the boxes are being overfilled?

a)

1 sample z-test

b)

2 sample t-test

c)

1 proportion z-test

d)

1 sample t-test

122.

Which of the following is the most appropriate interval for the manager to use for such an estimate?

a)

A

b)

B

c)

C

d)

D

e)

E

123.

A town council wants to estimate the proportion of residents who are in favor of a proposal to upgrade the computers in the town library. A random sample of 100 residents was selected, and 97 of those selected indicated that they were in favor of the proposal. Is it appropriate to assume that the sampling distribution of the sample proportion is approximately normal?

a)

A

b)

B

c)

C

d)

D

e)

E

124.

Suppose a researcher wants to use a confidence interval to estimate an unknown population proportion p. Which of the following is not a correct statement?

a)

The endpoints of the interval can vary with each new sample.

b)

The probability that p is in the interval is equal to the level of confidence for the interval.

c)

Whether the interval captures p is not known with certainty.

d)

The population proportion p is fixed, but the sample proportion p^ can vary from sample to sample.

e)

The interval either does or does not capture p.

125.

A hypothesis test was conducted to investigate whether the population proportion of students at a certain college who went to the movie theater last weekend is greater than 0.2. A random sample of 100 students at this college resulted in a test statistic of 2.25. Assuming all conditions for inference were met, which of the following is closest to the p-value of the test?

a)

0.0061

b)

0.0122

c)

0.0244

d)

0.9756

e)

0.9878

126.

Consider a 90 percent confidence interval constructed to estimate the difference between two population proportions. Which of the following is the best interpretation of what is meant by 90 percent confidence?

a)

The probability that the true difference in population proportions falls within the bounds of the confidence interval is 0.90.

b)

For repeated random sampling from the populations with samples of the same size, approximately 90% of the sample proportions will fall within the bounds of the confidence interval.

c)

If the sampling process is repeated 10 times, 9 intervals will capture the true difference between the population proportions and 1 interval will not.

d)

For repeated random sampling from the populations with samples of the same size, approximately 90% of the confidence intervals constructed will capture the true difference between the population proportions.

e)

For repeated random sampling from the populations with samples of the same size, approximately 90% of the confidence intervals constructed will capture the sample difference between the population proportions.

127.

In the United States, 36 percent of the people have a blood type that is A positive. From a random sample of 150 people from Norway, 66 had a blood type that was A positive. Consider a hypothesis test to investigate whether the proportion of people in Norway with a blood type of A positive is different from that in the United States. Which of the following is the standard deviation used to calculate the test statistic for the one-sample z-test?

a)

A

b)

B

c)

C

d)

D

e)

E

128.

In a hypothesis test for a single proportion, which of the following is assumed for the calculation of the p-value?

a)

The alternative hypothesis is true.

b)

The null hypothesis is true.

c)

The distribution of the population is approximately normal.

d)

The sample proportion is equal to the hypothesized proportion.

e)

The sample size is 30 or more.

129.

Zoie completes a report by asking 70 students across campus. She found that 48% of CIAA students do not wash their hands after using the bathroom. What is the population of her survey?

a)

the bathroom

b)

CIAA students

c)

48% of students

130.

Zoie completes a report by asking 70 students across campus. She found that 48% of CIAA students do not wash their hands after using the bathroom. What is the sample size?

a)

48

b)

100

c)

70

d)

CIAA students

131.

A recent survey of 800 seventh graders from across the state shows 4 out of 10 like to play paper football. How many students said they like to play paper football?

a)

40 students

b)

200 students

c)

320 students

d)

8,000 students

132.

There are 400 students at Polly's school. She surveyed a random sample of 80 students to find their favorite hobby. 19 said they like to read. 30 said they like to be with friends. 8 said they like to do crafts. 23 said they like to play sports. Polly infers that doing crafts is the least popular hobby at her school.

Refer to the data table. Polly surveys two more samples. Do the results from these samples support the inference made from the first sample?

a)

Yes, the survey results support the inference that doing crafts is the least popular hobby at Polly's school.

b)

No, the survey results does not support the inference that doing crafts is the least popular hobby at Polly's school.

133.

There are 400 students at Polly's school. She surveyed a random sample of 80 students to find their favorite hobby. 19 said they like to read. 30 said they like to be with friends. 8 said they like to do crafts. 23 said they like to play sports. Polly infers that doing crafts is the least popular hobby at her school.

Yovani estimates that about 200 students in the school favor playing sports as a hobby. Do you agree?

a)

Yes, I used a proportion to find the number of students in the school who likely to prefer to play sports. 23/80 = 200/400; 200 students

b)

No, I used a proportion to find the number of students in the school who likely to prefer to play sports. 23/80 = 115/400; 115 students

134.

The dot plots show how long it took students in Mr. Chauncey's two science classes to finish their science homework last night. Find the means to make an inference about the data.

a)

The 1st period mean is 35. The 2nd period mean is 38.75. On average, it took students in the 1st period class slightly longer to finish their homework than it did the students in the 2nd period class.

b)

The 1st period mean is 38.75. The 2nd period mean is 35. On average, it took students in the 1st period class slightly longer to finish their homework than it did the students in the 2nd period class.

c)

The 1st period mean is 35. The 2nd period mean is 38.75. On average, it took students in the 2nd period class slightly longer to finish their homework than it did the students in the 1st period class.

d)

The 1st period mean is 38.75. The 2nd period mean is 35. On average, it took students in the 2nd period class slightly longer to finish their homework than it did the students in the 1st period class.

135.

Litzy collects data from a random sample of 7th graders. Out of 40 respondents, 7 attend afterschool programs. Of the 200 7th graders attending Litzy's school, how many would be expected to attend afterschool programs?

a)

14 7th graders

b)

28 7th graders

c)

35 7th graders

d)

42 7th graders

136.

Trinity surveys students in her computer class about time spent on computers by students in her school. Fill in the blank to explain why this is not a representative sample. This is not a representative sample because students in computer class are _________ to use computers than other students.

a)

less likely

b)

equally likely

c)

more likely

137.

The dot plot shows a random sample of the number of fish caught and released by 30 participants during a two-day fishing tournament. Select the inference that can be made based on the data collected.

a)

On average, most participants caught and released 5 or more fish.

b)

More participants caught 6 fish than any other number.

c)

The same participants who caught and released 1 fish the first day caught and released 1 fish on the second day.

d)

On average, participants caught and released more fish on Day 2.

138.

The captain of the basketball team wants to determine where the team should go for their end-of-season celebration. Which of the following is a representative sample? Select all that apply.

a)

The students in her homeroom

b)

Players whose names are randomly selected from a hat

c)

The players in the starting lineup

d)

All players over 5 feet tall

e)

Every 5th player selected from an alphabetical roster of the team

139.

_______ is the entire group of objects or individuals considered for a survey.

a)

Sample

b)

Population

c)

Random Sample

d)

Quartile

140.

_______ is a part of a group being surveyed.

a)

Sample

b)

Population

c)

Random Sample

d)

Quartile

141.

A sample should be

a)

representative of only middle school students only

b)

a very large group

c)

representative of the population

d)

representative of people who volunteer

142.

Anthony opened a new store and wants to conduct a survey to determine the best store hours. Which is the best representative sample?

a)

A group of randomly selected people who come to the store in one week.

b)

A group of randomly selected people who visit his website on one night.

c)

Every person he meets at his health club one night.

d)

The first 20 people who walk into his store one day.

143.

12 ounce shampoo bottle lasts Mike 16 weeks. How long would you expect an 18-ounce bottle of the same brand to last him?

a)

24 weeks

b)

6 weeks

c)

30 weeks

d)

20 weeks

144.

According to a random telephone survey of 200 adults, 75% of all working adults in the U.S. are satisfied with their current job. What is the population in this survey?

a)

200 adults

b)

adults in the U.S.

c)

75% of adults

145.

Studies have shown that their is a higher cancer rate of people who worked around asbestos than people who are not exposed to asbestos. Asbestos is now illegal to use in construction. What inference can we make from this.

a)

Asbestos does not cause cancer

b)

Exposure to asbestos may increase your risk of cancer

c)

There probably is no connection

d)

Cannot make a determination

146.

Data has determined that the probability of getting a ticket is greater if you drive a red car. Would it be fair to generalize that driving a red vehicle of any type would increase your chances of getting a ticket?

a)

Yes because there is a direct correlation

b)

No there may be a lurking variable.

147.

If you are able to determine a direct correlation between two variables but can identify one or more confounding variables, can you make an inference between the two correlated variables?

a)

Yes

b)

No

c)

Sometimes

148.

There are two male high school students. One is considerably taller than the other. What could you generalize?

a)

The taller student plays basketball

b)

The shorter student does not eat well

c)

The taller student is older

d)

Nothing

149.

If no alpha level is given, what alpha level is assumed?

a)

0.01

b)

0.05

c)

0.10

d)

0.25

150.

If no p-hat value is given, what should you assume p-hat equals?

a)

0.01

b)

0.05

c)

0.10

d)

0.5

151.

Which of the following hypotheses is a valid example of a 1-tailed test?

a)

Ho: p = 0.3, Ha: p > 0.4

b)

Ho: p = 0.3, Ha: p ≠ 0.3

c)

Ho: p^ = 0.3, Ha: p^ > 0.3

d)

Ho: p = 0.3, Ha: p > 0.3

152.

A confidence interval estimate is determined from the summer earnings of a SRS of n students. All other things being equal, which of the following will result in a smaller margin of error?

a)

A greater confidence level

b)

A larger sample standard deviation

c)

A larger sample size

d)

Introducing bias into sampling

153.

Two confidence interval estimates from the same sample are (0.72, 0.83) and (0.75, 0.81). One is at 95%, the other is at 99%. Which is which?

a)

(0.72, 0.83) is at 99%

b)

(0.72, 0.83) is at 95%

c)

Need to know sample size to determine this

d)

Need to know standard error to determine this

154.

When leaving for school, you make a judgement on these hypotheses. Ho: The weather will remain dry. Ha: It will rain. What are the results of the Type I and Type II errors?

a)

Type I: Needlessly carry around an umbrella all day. Type II: Get drenched

b)

Type I: Get drenched. Type II: Needlessly carry around an umbrella all day

c)

Type I: Carry umbrella & it rains. Type II: Carry no umbrella & it doesn't rain

d)

Type I: Get drenched. Type II: Carry umbrella & it rains

155.

Tina wants to know if the proportion of people who buy burgers is at all affected by her open mic reading. If p=0.8 before her reading, what is an appropriate set of hypotheses?

a)

Ho: p = 0.8
Ha: p > 0.8

b)

Ho: p = 0.8
Ha: p < 0.8

c)

Ho: p ≠ 0.8
Ha: p = 0.8

d)

Ho: p= 0.8
Ha: p ≠ 0.8

156.

Which of the following is true?

a)

We do not use sample statistics when stating hypotheses

b)

P-value = 0.05 means the probability that the null is true is 0.05

c)

If the p-value is small enough, we can conclude that the alternate hypothesis is true

d)

You must examine your data prior to deciding to do a 1- or 2-tailed test

157.

Under what conditions would it be meaningful to construct a confidence interval estimate when the data consist of the entire population?

a)

If the population size is large (n > 30)

b)

If a higher level of confidence is desired

c)

If the population is truly random

d)

Never

158.

A credit card company would like to compare the proportion of people who have poor credit to the proportion of people who think they have poor credit. Which of the following is most appropriate?

a)

1-Proportion Z-Test

b)

1-Proportion Z-Interval

c)

2-Proportion Z-Test

d)

2-Proportion Z-Interval

159.

A 99% confidence interval found that the true proportion of teens who drink coffee every day is in the interval (0.785, 0.831). What was the p^ value used to determine this interval?

a)

0.8

b)

0.808

c)

0.825

d)

0.831

160.

What is the z* value for a 88%confidence interval?

a)

1.175

b)

1.555

c)

1.645

d)

1.96

161.

What type of error occurs when the null hypothesis is not true, but we fail to reject it?

a)

Type I

b)

Type II

c)

This can be either Type I or Type II

d)

This is not an error

162.

Which of the following is true pertaining to a 2-proportion z-interval?

a)

There are no restrictions on sample size

b)

This interval can be found even if the samples are not random

c)

The population should be large, relative to each of the sample sizes

d)

So long as all conditions are met for one sample, you do not need to check conditions for the other sample

163.

What additional condition must be checked for a 2-proportion test or interval compared to a 1-proportion test or interval?

a)

You must make sure that the samples are random

b)

You must make sure that the two samples are independent from one another

c)

You must make sure that the sum of the samples' sizes are smaller than 10% of the whole population

d)

The conditions are exactly the same

164.

In a past General Social Survey, a random sample of men and women answered the question “Are you a member of any sports clubs?” Based on the sample data, 95% confidence intervals for the population proportion who would answer “yes” are .13 to .19 for women and .247 to .33 for men. Based on these results, you can reasonably conclude that

a)

At least 25% of American men and American women belong to sports clubs.

b)

At least 16% of American women belong to sports clubs.

c)

There is a difference between the proportions of American men and American women who belong to sports clubs.

d)

There is no conclusive evidence of a gender difference in the proportion belonging to sports clubs

165.

Null and alternative hypotheses are statements about:

a)

population parameters.

b)

sample parameters.

c)

sample statistics.

d)

it depends - sometimes population parameters and sometimes sample statistics.

166.

A test was conducted to see if there was evidence that more than 10% of the population is left-handed. Ho: p = 0.10, Ha: p >0.10. A p-value of 1.10 is found. What can we conclude?

a)

There is not evidence that more than 10% of people are left-handed

b)

We can conclude that more than 10% of people are left-handed

c)

There is evidence that more than 10% of people are left-handed

d)

The person who ran this test made an error

167.

Conduct a test to determine whether or not the population proportion of voters in favor of proposal A is greater than 50%. In a random sample of 200 voters, 140 said that they were in favor of this proposal. Compute the test statistic.

a)

z = 6.17

b)

z = 5.66

c)

z = 19.80

d)

None of the above

168.

The null and alternative hypotheses divide all possibilities into:

a)

two sets that overlap

b)

two non-overlapping sets

c)

two sets that may or may not overlap

d)

as many sets as necessary to cover all possible outcomes

inference for 2

Total questions: 168

Worksheet time: 9hrs 1mins

You are thinking of conducting a one-sample t-test about a population mean $\mu$ using a 0.05 significance level. Which of the following statements is correct?

You should not carry out the test if the sample does not have a Normal distribution

You can safely carry out the test if there are no outliers, regardless of the sample size

You can carry out the test if a graph of the data shows no strong skewness, regardless of the sample size.

You can carry out the test only if the population standard deviation is known

You can safely carry out the test if your sample size is at least 30

Similar Resources on Wayground

inference for 2

Total questions: 168

Worksheet time: 9hrs 1mins

You are thinking of conducting a one-sample t-test about a population mean μ\muμ using a 0.05 significance level. Which of the following statements is correct?

You should not carry out the test if the sample does not have a Normal distribution

You can safely carry out the test if there are no outliers, regardless of the sample size

You can carry out the test if a graph of the data shows no strong skewness, regardless of the sample size.

You can carry out the test only if the population standard deviation is known

You can safely carry out the test if your sample size is at least 30

Similar Resources on Wayground

You are thinking of conducting a one-sample t-test about a population mean $\mu$ using a 0.05 significance level. Which of the following statements is correct?