WorksheetsAP Stats (All test combined MCQ)
Total questions: 100
Worksheet time: 50mins
The pie chart at right describes the distribution of state tree types for the 50 states in the United States. The category "Other" include all trees that are the state tree for two or fewer states. Which of the following conclusions can we draw from this chart?
Some states have not designated a "state tree"
The cottonwood is the state tree for 12 states
Taken together, oak, pine, and maple are the state trees for more than half the states
There are 10 states that have designated a pine as their state tree
There is no state that has designated the Eastern Red Cedar as its state tree
The median age of five people in a meeting is 30 years. One of the people, whose age is 20 years, leaves the room. The median age of the remaining four people in the room is
40 years
30 years
25 years
more than 30 years
Cannot be determined from the information given
The mean age of five people in a meeting is 30 years. One of the people, whose age is 20 years, leaves the room. The mean age of the remaining four people in the room is
40 years
30 years
25 years
more than 30 years
cannot be determined from the information given
Which of the following statements is NOT true
In a symmetric distribution, the median is halfway between the first and third quartiles
The first quartile is equivalent to the twenty-fifth percentile
The range is the difference between the largest and the smallest observation in the data set.
The median is always greater than the mean
In a symmetric distribution, the mean and median are equal
Here are the IQ test scores of 10 randomly chosen fifth-grade students:
145, 139, 126, 122, 125, 130, 96, 110, 118, 118
To make a stemplot of these scores, you would use as stems
0 and 1
09, 10, 11, 12, 13, and 14
0, 2, 3, 5, 6, 8, 9
96, 110, 118, 122, 125, 126, 130, 139, and 145
none of the above is a correct answer
A medical researcher collects health data on many women in each of several countries. One of the variables measured for each woman in the study is her weight in pounds. The following list gives the five-number summary for the weights of women in one of the countries
Country A: 100, 110, 120, 160, 200
About what percent of Country A women weigh between 110 and 160 pounds?
95%
75%
65%
50%
25%
The weights of the male and female students in a class are summarized in the following boxplots. Which of the following is NOT correct?
The median weight of male students is about 162 pounds
About 25% of female students have weight more than 130 pounds
About 50% of the male students have weights between 150 and 185 pounds
The mean weight of female students is about 120 pounds because of symmetry
The male students have less variability than female students
Consider the following ogive {relative frequency graph} of the scores of students in an introductory statistics course
A grade of C or C+ is assigned to a student who scores between 55 and 70. The percentage of students who obtained a grade of C or C+ is
25%
30%
20%
50%
15%
If a distribution is skewed to the left,
The mean is less than the median
The mean and median are equal
The mean is greater than the median
It's impossible to tell without seeing the data
None of the above is a correct answer
A survey records many variables of interest to the researchers conducting the survey. Which of the following variables, from a survey conducted by the U.S. Postal Service, is categorical?
Age of respondant
Number of people, both adults and children, living in the household
Years lived at that address
State of residence
Total household income, before taxes, in 1993
A sample of 250 high school students were asked, "If you had $1000 to contribute to one kind of charitable organization, which type of organization would you choose? Below is a two-way table of responses to this question and gender. Which of the following conclusions seems to be supported by the data?
Most of the females who chose a health organization would have chosen an environmental organization as their second choice, had they been asked
There is no association between gender and choice of organization
The proportion of males who said they would contribute to an environmental organization was higher than the proportion of females who said they would contribute such an organization
None of the students surveyed said they would contribute to religious organizations
The marginal distribution or organization is 140, 110
The population of the United States is aging, though less rapidly than in other developed countries. At right is a stemplot of the percentages of residents aged 65 and older in each of the 50 states, according to the 2010 census. There are three outliers: Alaska has the lowest percentage of older residents, Utah had the second lowest, and Florida has the highest. What is the percentage for Utah?
7.7%
9%
14%
15%
90%
The density curve shown to the right takes the value 0.5 on the interval 0 < X < 2 and takes the value 0 everywhere else. What percent of the observations lie between 0.5 and 1.2?
25%
35%
50%
68%
70%
For the density curve shown at the right, which statement is true?
The mean is greater than the median
The mean is less than the median
The mean and median are equal
The mean could be either greater than or less than the median
None of the above is correct
The heights of American men aged 18 to 24 are approximately Normally distributed with a mean of 68 inches and a standard deviation of 2.5 inches. Only about 5% of young men have heights outside the range
65.5 inches to 70.5 inches
63 inches to 73 inches
60.5 inches to 75.5 inches
58 inches to 78 inches
None of the above
The heights of American men aged 18 to 24 are approximately Normally distributed with a mean of 68 inches and a standard deviation of 2.5 inches. About what percentage of them are over 70.5 inches tall?
2.5
5
16
32
68
The graph below is a Normal probability plot for the amount of rainfall (in acre-feet) obtained from 26 randomly selected clouds that were seeded with silver oxide. Which of the following statements about the shape of the rainfall distribution is true?
The distribution is Normal
The distribution is approximately normal
The distribution is skewed left
The distribution has no potential outliers
The distribution is skewed right
Which of the following properties is true for all Normal density curves?
I. they are symmetric
II. The curve reaches its peak at the mean
III. 95% of the area under the curve is within one standard deviation of the mean
I only
II only
I and II only
I and III only
All three statements are correct
The distribution of the time it takes for different people to solve a certain crossword puzzle is strongly skewed to the right, with a mean of 30 minutes and a standard deviation of 15 minutes. The distribution of z-scores for those times is
Normally distributed, with mean 30 and standard deviation 15
Skewed to the right, with mean 30 and standard deviation 15
Normally distributed, with mean 0 and standard deviation 1
Skewed to the right, with mean 0 and standard deviation 1
Skewed to the right, but the mean and standard deviation cannot be determined without more information
The cumulative relative frequency graph at the right shows the distribution of lengths (in centimetres) of fingerlings at the fish hatchery. The interquartile range for this distribution is approximately:
0.18 to 0.85 centimeters
5 to 7 centimeters
5.5 to 6.7 centimeters
1.2 centimeters
2 centimetres
The proportion of scores in a standard Normal distribution that are greater than 1.25 is closest to:
.1056
.1151
.1600
.8849
.8944
Kitchen appliances don't last forever. The lifespan of all microwave ovens sold in the United States is approximately Normally distributed with a mean of 9 years and a standard deviation of 2.5 years. What percentage of the ovens last more than 10 years?
11.5%
34.5%
65.5%
69%
84,5%
A standard normal distribution has
A mean of 1 and a standard deviation of 1
A mean of 0 and a standard deviation of 0
A mean of 1 and a standard deviation of 0
A mean of 0 and a standard deviation of 1
None of these
The distribution of heights of students in a large class is roughly Normal. Moreover, the average height is 68 inches, and approximately 95% of the heights are between 62 and 74 inches. Thus, the standard deviation of the height distribution is approximately equal to
2
3
6
9
12
In a statistics course, a linear regression equation was computed to predict the final-exam score from the score on the first test. The equation was ŷ=10 + 0.9x where y is the final exam score and x is the score on the first test. Carla scored 95 on the first test. What is the predicted value of her score on the final exam?
85.5
90
95
95.5
none of these
In a statistics course, a linear regression equation was computed to predict the final-exam score from the score on the first test. The equation was ŷ=10 + 0.9x where y is the final exam score and x is the score on the first test. Bill scored a 90 on the first test and a 93 on the final exam. What is the value of his residual
-2
2
3
93
none of these
You have data for many families on the parents' income and the years of education their eldest child completes. Your initial examination of the data indicates that children from wealthier families tend to go to school for longer. When you make a scatterplot
The explanatory variable is parent's income, and you expect to see a negative association
The explanatory variable is parent's income, and you expect to see a positive association
The explanatory variable is parent's income, and you expect to see very little association
The explanatory variable is years of education, and you expect to see a negative association
The explanatory variable is years of education, and you expect to see a positive association
The correlation between the heights of fathers and the heights of their (fully grown) sons is r = 0.52. This value was based on both variables being measured in inches. If fathers' heights were measure in feet (one foot equals 12 inches), and son's heights were measured in furlongs (one furlong equals 7920 inches), the correlation between heights of fathers and heights of sons would be
much smaller than 0.52
slightly smaller than 0.52
unchanged: equal to 0.52
Slightly larger than 0.52
Much larger than 0.52
A community college announces that the correlation between college entrance exam grades and scholastic achievement was found to be -1.08. On the basis of this you would tell the college that
The entrance exam is a good predictor of success
The exam is a poor predictor of success
Students who do best on this exam will be poor students
Students at this school are underachieving
The college should hire a new statistician
An agricultural economist says that the correlation between corn prices and soybean prices is r = 0.7. This means that
When corn prices are above average, soybean prices also tend to be above average
There is almost no relation between corn prices and soybean prices
When corn prices are above average, soybean prices tend to be below average
When soybean prices go up by 1 dollar, corn prices go up by 70 cents
The economist is confused, because correlation makes no sense in this situation
A copy machine dealer has data on the umber of copy machines x at each of 89 customer locations and the number of service calls in a month y at each location. Summary calculations give x = 8.4, sx = 2.1, y = 14.2, sy = 3.8, and r = 0.86. What is the slope of the least-squares regression line of number of service calls on number of copiers?
0.86
1.56
0.48
2.82
Can't tell from the information given
There is an approximate linear relationship between the height of females and their age (from 5 to 18 years) described by the equation Height = 50.3+6.1(age), where height is measured in centimeters and age in years. Which one of the following statements must be true?
The estimated slop is 6.1, which implies that female children between the ages 5 and 18 increase in height by about 6.1 cm for each year they grow older
The correlation between height and age is negative
The estimated intercept is 50.3 cm. We can conclude from this that the typical height of female children at birth is 50.3 cm
The heights of 68% of female children who are 10 years old are within 6.1 cm. of 110.4 cm
My niece is 8 years old and is 115 cm tall. She is shorter than average for girls her age
Which of the following are true statements?
I. Correlation requires that there are clearly-identified explanatory and response variables.
II. Scatterplots require that both variables be quantitative
III. Every least-squares regression line passes through (x,y)
I and II only
II and III only
None of these
I and III only
I, II, and III
A study of the fuel economy for various automobiles plotted the fuel consumption (in liters of gasoline used per 100 kilometers traveled) vs. speed (in kilometers per hour). A least squares line was fit to the data. Here is the residual plot from this least-squares fit
What does the residual plot tell you about the linear model?
The residual plot confirms the linearity of the fuel economy data
The residual plot does not confirm nor rule out the linearity of the data
The residual plot suggests that the model may be linear, but more data points are needed to confirm this
The residual plot clearly indicates that the data isn't linear
A residual plot is not an appropriate means for evaluating a linear model
One concern about the depletion of the ozone layer is that the increase in ultraviolet (UV) light will decrease crop yields. An experiment was conducted in a green house where soybean plants were exposed to varying levels of UV, measured in Dobson units. At the end of the experiment the yield (kg) was measured. A regression analysis was performed with the following results. The least-squares regression line is the line that
Minimizes the sum of the distances between the actual UV values and the predicted UV values
Minimizes the sum of the squared residuals between the actual yield and the predicted yield
Minimizes the sum of the distances between the actual yield and the predicted UV
Minimizes the sum of the squared residuals between the actual UV reading and the predicted UV values
Minimizes the perpendicular distance between the regression line and each data point
One concern about the depletion of the ozone layer is that the increase in ultraviolet (UV) light will decrease crop yields. An experiment was conducted in a green house where soybean plants were exposed to varying levels of UV, measured in Dobson units. At the end of the experiment the yield (kg) was measured. A regression analysis was performed with the following results. Which of the following is correct?
If the UV value increases by 1 Dobson unit, the yield is expected to increase by .0463 kg
If the yield increases by 1 kg, the UV value is expected to decrease by .0463 Dobson units
If the UV increases by 1 Dobson unit, the yield is expected to decrease by .0463 kg
The predicted yield is 4.3 kg when the UV value is 20 Dobson units
None of the above is correct
A new headache remedy was given to a group of 25 subjects who had headaches. Four hours after taking the new remedy, 20 of the subjects reported that their headaches had disappeared. From this information you conclude
That the remedy is effective for the treatment of headaches
Nothing, because the sample size is too small
Nothing, because there is no control group for comparison
That the new treatment is better than aspirin
That the remedy is not effective for the treatment of headaches
The following numbers appear in a table of random digits
38683 50279 38224 09844 13578 28251 12708 24684
A scientist will be measuring the total amount of leaf litter in al random sample (n = 5) of forest sites selected without replacement from a population of 45 sites. The sites are labeled 01, 02, . . . , 45 and she starts at the beginning of the line of random digits and takes consecutive pairs of digits. Which of the following is correct?
Her sample is 38, 25, 02, 38, 22
Her sample is 38, 68, 35, 02, 22
Her sample is 38, 35, 27, 28, 08
Her sample is 38, 65, 35, 02, 79
Her sample is 38, 35, 02, 22, 40
What electrical changes occur in muscles as they get tired? Student subjects are instructed to hold their arms above their shoulders as long as they can. Meanwhile, the electrical activity in their arm muscles is measured This is
An observational study
An uncontrolled experiment
A randomized comparative experiment
A matched pairs design
Impossible to describe unless more details of the study are provided
A maple sugar manufacturer wants to estimate the average trunk diameter of Sugar Maple trees in a large forest. There are too many trees to list them all and take a SRS, so he divides the forest into several hundred 10 meter plots, selects 25 plots at random, and measures the diameter of every Sugar Maple in each one. This is an example of a
Multistage sample
Stratified sample
Simple random sample
Cluster sample
Convenience sample
A researcher for a consumer products company is field testing a new formula for laundry detergent. He has contracted with 60 families, each with two children, who have agreed to test the product. He randomly assigns 30 families to the group that will use the new formula and 30 to the group that will sue the company's current detergent formula. The most important reason for this random assignment is that
Randomization makes the analysis easier since the data can be collected and entered into the computer in any order
Randomization eliminates the impact of any confounding variables
Randomization is a good way to create two groups of 30 families that are as similar as possible, so that comparisons can be made between the two groups
Randomization ensures that the study is double-blind
Randomization reduces the impact of outliers
To test the effect of music on productivity, a group of assembly line workers are given portable mp3 players to play what ever music they choose while working for one month. For another month, they work without music. The order of the two treatments for each worker is determined randomly. This is
An observational study
A matched pairs experiment
A completely randomized experiment
a block design, but not a matched pairs experiment
Impossible to classify unless ore details of the study are provided
A survey was done in the town of Mechanicsville to estimate the proportion of cars that are red and made by companies based in Japan. A simple random sample of 25 cars from a parking lot at Lee-Davis High School was taken. Which of the following statements is correct?
Since this is a simple random sample, it should be representative of all the cars in Mechanicsville
If a simple random sample fo 15 cars were taken, we would expect the same amount of variability in the proportion of red cars as we would with the sample of 25 cars
An alternative method for getting a representative sample would be to select the 25 cars closest to a specified location, such as the entrance to the gymnasium
A different team doing the sampling independently would probably obtain a slightly different answer for their sample proportion
The results would be the same regardless of teh time of day that the sample is taken
A nutritionist wants to study the effect of storage time (6, 12, and 18 months) on the amount of vitamin C present in freeze dried fruit when stored for these lengths of time. Six fruit packs were randomly assigned to each of the three storage times. The treatment, experimental unit, and response are respectively
A specific storage time, amount of vitamin C, a fruit pack
A fruit pack, amount of vitamin C, a specific storage time
Random assignment, a fruit pack, amount of vitamin C
A specific storage time, a fruit pack, amount of vitamin C
A specific storage time, six fruit packs, amount of vitamin C
A researcher observes that, on average, the number of divorces in cities with Major League Baseball teams is larger than in cities without Major League Baseball teams. Which of the following is the most plausible explanation for this observed association?
The presence of a Major League Baseball team causes the number of divorces to rise (perhaps husbands are spending too much time at the ballpark)
The high number of divorces is responsible for the presence of major league baseball teams (more single men means potentially more fans at the ballpark, making it attractive for an owner to relocate to such cities)
The association is due to confounding (Major league teams tend to be in large cities with more people, hence a greater number of divorces)
The association makes no sense, since many married couples go to the ballpark together
The association is purely coincidental. It is implausible to believe the observed association could be anything other than accidental
Control groups are used in experiments in order to accomplish which one of the following?
Limit the effects of variables other than the explanatory variable on the outcome
Control the subjects of a study to ensure that all participate equally
Guarantee that someone other than the investigators, who have a vested interested in the outcome, controls how the experiment is conducted
Achieve a proper and uniform level of randomness
Reduce variability in results
A survey is to be administered to recent graduates of a certain nursing school in order to compared the starting salaries of women and men. For a random sample of graduates, three variables are to be recorded: sex, starting salary, and area of specialization. Which of the following best describes a conclusion that can be drawn from this study?
Whether being female causes graduates of this nursing school to have lower (or higher) starting salaries than males
Whether being female causes graduates in this sample to have lower (or higher) starting salaries than males
Whether choosing a certain area of specialization causes females graduates of this nursing school to have lower (or higher) starting salaries than males
Whether there is an association between sex and starting salary among graduates of this nursing school
Whether there is an association between sex and starting salary at all nursing schools
For a certain experiment you have 8 subjects, of which 4 are female and 4 are male. The name of the subjects are listed below:
Male: Atwater, Bacon, Chu, Diaz
Female: Johnson, King, Liu, Moore
There are to be two treatment groups, A and B. If a randomized block design is used, with the subjects blocked by their gender, which of the following is not a possible group of subjects for treatment group A?
Atwater, Chu, King, Liu
Bacon, Chu, Liu, Moore
Atwater, Diaz, Liu, King
Atwater, Bacon, Chu, Johnson
Atwater, Bacon, Johnson, King
A randomly selected student is asked to respond Yes, No, or Maybe to the question "Do you intend to vote in the next presidential election?" The sample space is {Yes, No, Maybe}. Which of the following represents a legitimate assignment of probabilities for this sample space?
0.4, 0.4, 0.2
0.4, 0.6, 0.4
0.3, 0.3, 0.3
0.5, 0.3, -.2
None of the above
If you choose a card at random from a well-shuffled deck of 52 cards, what is the probability that the card chosen is not a heart?
.25
.5
.75
1
None of the above
A basketball player shoots 8 free throws during a game. The sample space for counting the number she makes is
S = any number between 0 and 1
S = whole numbers 0 to 8
S = all sequences of 8 hits or misses, like HMMHHHMH
S = {HMMMMMMM, MHMMMMMM, MMHMMMMM, MMMHMMMM, MMMMHMMM, MMMMMHMM, MMMMMMHM, MMMMMMMMH}
None of the above
If P(A) = 0.24 and P(B) = 0.52 and A and B are independent, what is P(A or B)
0.1248
0.28
0.6352
0.76
The answer cannot be determined from the information given
Which of the following pairs of events are disjoint (mutually exclusive)?
A: the odd numbers; B: the number 5
A: the even number; B: the numbers greater than 10
A: the numbers less than 5; B: all negative numbers
A: the numbers above 100; B: the numbers less than -200
A: negative numbers; B: odd numbers
Of people who died in the United States in a recent year, 86% were white, 12% were black, and 2% were Asian (we will ignore the small number of deaths among other races) Diabetes causes 2.8% of deaths among whites, 4.4% among black, and 3.5% among Asians. The probability that a randomly chosen death was due to diabetes is about
.96
.107
.042
.038
.030
Government data give the following counts of violent deaths in a recent year among people 20 to 24 years of age by sex and cause of death:
Choose a violent death in this age group at random. The probability that the victim was male is about
.81
.78
.59
.46
.19
Government data give the following counts of violent deaths in a recent year among people 20 to 24 years of age by sex and cause of death:
The conditional probability that the victim was male, given that the death was accidental is about
0.46
0.48
0.56
0.78
0.81
Government data give the following counts of violent deaths in a recent year among people 20 to 24 years of age by sex and cause of death:
The conditional probability that the death was accidental, given that the victim was male, is about
0.81
0.56
0.78
0.48
0.46
Government data give the following counts of violent deaths in a recent year among people 20 to 24 years of age by sex and cause of death:
Let A be the even that a victim of violent death was a woman and B the event that the death was a suicide. The proportion of suicides among violent deaths of women is expressed in probability notation as
0.132
0.138
P(A and B)
P(A|B)
P(B|A)
In your top dressed drawer are 6 blue socks and 10 grey socks, unpaired and mixed up. One dark morning you pull two socks from the drawer (without replacement of course) what is the probability that the two socks match?
0.075
0.375
0.450
0.5
0.550
An even A will occur with probability 0.5. An event B will occur with probability 0.6. The probability that both A and B will occur is 01. The conditional probability of A, given B
Is 1/2
Is 3/10
Is 1/5
Is 1/6
Cannot be determined from the information given
A marketing survey compiled data on the total number of televisions in households. If X = the number of televisions in a randomly-selected household, and we omit the rare cases of more than 5 televisions, then X has the following distribution:
What is the probability that a randomly chosen household has at least two televisions?
0.19
0.20
0.29
0.39
0.61
A business evaluates a proposed venture as follows. It stands to make a profit of $10,000 with probability 3/20, to make a profit of $5000 with probability 9/20, to break even with probability 5/20, and to lose $5000 with probability 3/20. The expected profit in dollars is
1500
0
3000
3250
-1500
A randomly chosen subject arrives for a study of exercise and fitness and begins walking on a treadmill at a brisk pace. Which of the random variables described below is discrete?
You measure the maximum heart rate in beats per minute
You measure VO2, the maximum volume of oxygen consumed per minute during exercise. VO2 is generally between 2.5 liters per minute and 6 liters per minute
You measure the subjects walking speed in miles per hour
You measure the amount of time (in minutes) a subject walks on a treadmill before his or her heart rate reaches 120 beats per minute
You measure the time (in seconds) between the subject's heartbeats after 10 minutes of walking
Let the random variable X represent the profit made on a randomly selected day by a certain store. Assume that X is Normal with mean $360 and standard deviation $50. What is P(X>$400)?
0.2119
0.2881
0.5319
0.7881
0.8450
You select 40 cards from a standard deck of 52 cards. Let Y be the number of red cards (hearts of diamonds) in the 40 cards selected. Which of the following best describes this setting?
Y has a binomial with n = 40 observations and probability of success p = 0.5
Y has a binomial distribution with n = 40 observations and probability of success p = 0.5, provided the deck is shuffled well
Y has a binomial distribution with n = 40 observations and probability of success p = 0.5 provided that after selecting a card it is replaced in the deck and the deck is shuffled well before the next card is selected
Y has a geometric distribution with n = 40 observations and probability of success p = 0.5
Y has a geometric distribution with n = 52 observations and probability of success p = 0.5
Which of the following is a true statement?
The binomial setting requires that there are only two possible outcomes for each trial, while the geometric setting permits more than two outcomes
A geometric random variable takes on integer values from 0 to n
If X is geometric random variable and the probability of success is 0.85 then the probability distribution of X will be skewed left, since 0.85 is closer to 1 than 0
An important difference between binomial and geometric random variables is that there is a fixed number of trials in a binomial setting, and the number of trials varies in geometric setting
The distribution of every binomial random variable is skewed right
In order for the random variable X to have a geometric distribution, which one of the following conditions must X satify?
P < 0.5
The number of trials is fixed
X = the number of successes in n trials
The probability of success has to be the same for each trial
All outcomes in the sample space are equally likely
Jen's commute to work requires that she take the Blue subway line, then transfer to the Red line. The length of the trip on the Blue line has a mean of 18 minutes with a standard deviation of 2 minutes. The red line trip takes 12 minutes with a standard deviation of 1 minute. The waiting time between when she gets off the Blue line and her Red line train arrives has mean of 10 minutes and a standard deviation of 5 minutes. Assume (perhaps unrealistically) that these times are independent random variables. What are the mean and standard deviation of her entire commute?
Mean = 40 minutes; standard deviation = 8 minutes
Mean = 40 minutes; standard deviation = 5.48 minutes
Mean = 40 minutes; standard deviation =2.83 minutes
Mean = 30 minutes; standard deviation = 5.48 minutes
Mean 30 minutes; standard deviation = 8 minutes
It has been estimated that about 30% of frozen chickens are contaminated with enough salmonella bacteria to cause illness if improperly cooked. Chickens are delivered to grocery stores in crates of 24. Assume the chickens are independently selected for inclusion in the crate.
The probability that a certain crate has more than 4 contaminated chickens is
0.0424
0.0686
0.8889
0.9313
0.9576
According to the DuPont 2012 Global Automotive Color Popularity Report, 23% of all cars manufactured in 2012 were white. In a random sample of 100 cars parked in long-term parking at Philadelphia International Airport, 19% of the cars were white. Which of the following statements is true?
19% and 23% are parameters, 100 is a statistic
23% is a parameter, 19% is a statistic
23% is a statistic, 19% is a parameter
19%, 23% are statistics, 100 is neither a parameter nor a statistic
19%, 23% and 100 are all statistics
The best statistic for estimating a parameter has which of the following characteristics?
Low bias, high variability
High bias, high variaibility
Low bias, low variability
High bias, low variability
Low bias. Since a statistic should always equal the parameter it is estimating, there should be no variability
If a statistic used to estimate a parameter is such that the mean of its sampling distribution is equal to the true value of the parameter being estimated, what is the statistic said to be?
Random
A proprotion
Non-varing
Biased
Unbiased
Suppose you take a random sample of size 25 from a population wit mean of 120 and a standard deviation of 15. Your sample has a mean of 115 and a standard deviation of 13.8. Which of the following has a mean of 120 and a standard deviation of 3?
The distribution of the population
The distribution of the sample data
The sampling distribution of the sample mean
The sampling distribution of the population mean
No important distribution related to this situation has the given mean and standard deviation
In order to use the formula sigmax = (sigma/square root of n) to calculate the standard deviation of the sampling distribution of the sample mean, which of the following conditions must be met?
I. n> 30
II. The population's distribution is approximately normal
III.The sample size is less than 10% of the population size
I only
II only
III only
III and either I or II
I, II, and III
The central limit theorem refers to which of the following characteristic of the sampling distribution of the sample mean?
Regardless of the shape of the population's distribution, the sampling distribution of the sample mean from sufficiently large samples will be approximately normally distributed
Regardless of the shape of the population's distribution, the standard deviation of the sampling distribution of the sample mean from sufficiently larges samples will be (sigma/the square root of n)
Regardless of the shape of the population's distribution, the mean of the sampling distribution of the sample mean from sufficiently large samples will be equal to the mean of its population
As you take larger and larger samples from a normally distributed population, the standard deviation of the sampling distribution of the sample mean gets smaller and smaller
As you take larger and larger samples from a normally distributed population, the mean of the sampling distribution of the sample mean gets closer and closer to the population mean
The number of hours a light bulb burns before failing varies from bulb to bulb. The distribution of burnout times is strongly skewed to the right. The central limit theorem says that
As we look at more and more bulbs, their mean burnout time gets ever closer to the mean for all bulbs of this type
The mean burnout time for any number of bulbs has a distribution of the same shape ( strongly skewed) as the distribution for individual bulbs
The mean burnout time for any number of bulbs has a distribution that is close to normal
The mean burnout time for a large number of bulbs has a distribution of the same shape (strongly skewed_ as the distribution for individual bulbs
The mean burnout time for a large number of bulbs has a distribution that is close to normal
A simple random sample of 1000 Americans found that 62% were satisfied with the service provided by the dealer from which they bought their car . A simple random sample of 1000 Canadians found that 59% were satisfied with the service provided by the dealer from which they bough their car. The sampling variability associated with these statistics is
Exactly the same
Not exactly the same, but close
Much smaller for the sample of Canadians because the population of Canada is much smaller than that of the united States, hence the sample is a larger proportion of the population
Smaller for the sample of Canadians because the percent satisfied was smaller than that fro the Americans
Larger for the Canadians because Canadian citizens are more widely dispersed throughout the country that are citizens in the United States, hence they have more variable views
In an opinion poll, 25% of a random sample of 200 people said that they were strongly opposed to having a state lottery. The standard error of the sample proportion is approximately
0.0094
0.0306
0.0353
0.2500
6.1237
A marketing consultant wants to estimate the proportion of all shoppers at a certain mall who make at least one purchase. He stands at a mall exit for two hours on a weekday afternoon and flips a coin each time a shopper leaves. If the coin comes up heads, he asks them if they have made any purchases during the visit. After two hours, he has 132 responses, 104 of whom made a purchase. Which condition for constructing a confidence interval for a proportion has the consultant failed to satsify?
np>10
n(1-p)>10
n>30
The data is a random sample from the population of interest
The sample is less than 10% of the population
The report of a sample survey of 1,014 adults says, "With 95% confidence, between 9% and 15% of all Americans expect to spend more money on gifts this year than last year." What does the phrase "95% confidence" mean?
95% of all Americans will spend between 9% and 15% more than what they spent last year
9% to 15% of all Americans will spend 95% of what they spent last year
there is a 95% chance that the percent who expect to spend more is between 9% to 15%
The method used to get the interval from 9% to 15%, when used over and over, produces intervals which include the true population percentage about 95% of the time
We can be 95% confident that the method used to get the interval always gives the right answer
Some scientists believe that a new drug would benefit about half of all people with a certain blood disorder. To estimate the proportion of patients who would benefit from taking the drug, the scientists will administer it to a random sample of patients who have the blood disorder. What sample size is needed so that the 95% confidence interval will have a margin of error of no more than 3%?
748
1068
1503
2056
2401
The survey in the previous question was conducted by calling land-line telephones, and those conducting the survey are concerned about the possibility of undercoverage, since some people do not own a phone or own only a cell phone. Which of the following is the best way for them to correct for this source of bias?
Use a lower confidence level, such as 80%
Use a higher confidence level, such as 99%
Take a larger sample
Use a t-interval instead of a z-interval
Throw this sample out and start over again with a better sampling method
An SRS of 50 students at a large middle school are asked, "Do you have a television in your bedroom?" twenty-eight of the students responded "yes". If p = the proportion of students who answered "yes," what is the standard error of p?
0.005
0.010
0.070
0.106
The standard error cannot be calculated unless we know the standard deviation
A nationwide poll of 2,524 adults estimated with 95% confidence that the proportion of Americans who support health care reform is 0.78 plus or minus 0.0162. A member of congress thinks that 95% confidence isn't enough. He wants to be 99% confident. How would the margin of error of a 99% confidence interval based on the same sample compare with the 95% interval?
It would be smaller, because it omits only 1% of the possible samples instead of 5%
It would be the same, because the sample is the same
It would be larger, because higher confidence requires a larger margin of error
Can't tell, because the margin of error varies from sample to sample
Can't tell, because it depends on the size of the population
You want to calculate a 98% confidence interval for a population mean from a sample of n = 18. What is the appropriate critical t*
2.110
2.326
2.539
2.552`
2.567
The heights (in inches) of males in the United States are believed to be approximately Normally distributed with mean mu. The mean height of a random of 25 American adult males is found to be x = 69.72 inches and the standard deviation s = 4.15. What is the standard error of x?
0.17
0.69
0.83
1.856
2.04
In checking conditions for constructing confidence intervals for a population mean, it's important to plot the distribution of sample data. Below are dot plots describing samples from three different populations. For which for the three samples would it be safe to construct a t-interval?
Sample X only
Sample Y only
Sample Z only
Samples Y and Z
None of the samples
A 95% confidence interval for p, the proportion of all shoppers of all shoppers at a large grocery store who purchase cookies, was found to be (0.236, 0.282). The point estimate and margin or error for this interval are:
Point estimate = 0.236; Margin of error = 0.282
Point estimate =0.236; Margin of error = 0.046
Point estimate unknown; Margin of error = 0.023
Point estimate = 0.259; Margin of error = 0.046
Point estimate = 0.259; Margin of error = 0.023
A 95% confidence interval for p, the proportion of all shoppers of all shoppers at a large grocery store who purchase cookies, was found to be (0.236, 0.282).
Which of the following is a correct statement?
About 95% of the shoppers have between a 23.6% and a 23.2% chance of purchasing cookies
There is a 95% probability that the sample proportion lies between 0.236 and 0.282
If a second sample was taken, there is a 95% chance that its confidence interval would contain 0.25
This confidence interval indicates that more than 25% of shoppers buy cookies
We are reasonably certain the true proportion of shoppers who purchase cookies is between 24% and 28%
A significance test was performed to test the null hypothesis Ho : p + 0.5 versus the alternative Ha: p>0.5 the test statistic is z = 1.40. Which of the following is closest to the P-value for this test?
0.0808
0.1492
0.1616
0.2984
0.9192
A group of nutritionists is hoping to prove that a new soybean compound has more protein per gram than roast beef, which has a mean protein content of 20. A random sample of 5 batches of the soy compound have been tested, producing protein contents of 15, 22, 17, 18, and 23. Which of the following conditions must be met in order to carry out a legitimate statistical test of the nutritionists' claim?
I. The observations are from a normally distributed population
II. The data can be viewed as coming from a simple random sample
III. The standard deviation of the population is known
I only
II only
III only
Both I and II
I, II and III
Some people say that more babies are born in September than in any other month. To test this claim, you take a simple random sample of 150 students at your school and find that 21 of them were born in September. You are interested in whether the proportion born in September is higher than 1/12 - what you would expect if September was no different form any other month. Thus your null hypotheses is Ho: p=1/12. The P-value for your tests is 0.0056. Which of the following statements best describes what the P-value measures?
The probability that September birthdays are no more common than any other month is 0.0056
The probability the September birthdays are more common is 0.0056
The probability that the proportion of September birthdays in the population is not equal to 1/12 is 0.0056
0.0056 is the probability of getting a sample with a proportion of September birthdays this far or farther above 1/12 if the true proportion is 1/12
0.0056 is the probability of getting a sample with a proportion of September birthdays this close to 1/12 if the true proportion is not 1/12
Looking online, you find the salaries of all 25 players for the Chicago Cubs as of opening day of the 2013 baseball season. The club total was $104 million, fourteenth in the major leagues which inference procedure would you use to estimate the average salary of the Cubs players?
One-sample z interval for mu
One-sample t interval for mu
One-sample t test
One-sample z test
None of these- this is not a situation that calls for inference
A medical researcher is working on a new treatment for a certain type of cancer. After diagnosis, the average survival time on the standard treatment is two years. In an early trial, she tries the new treatment on the five subjects and finds that they have an average survival time of four years after diagnosis. Although the survival time has doubled, the results of a t-test for mean survival time are not statistically significant even at the 0.10 significance level. Which of the following is the best course of action for the researcher?
Since the test was not statistically significant, she should abandon the study of this treatment and move on to mlore promising ones
She should reexamine her computations- it is likely that she made an error
She should increase the significance level on her test so that she rejects the null hypothesis, since the treatment clearly has a positive impact
She should use a z-test instead of a t-test
She should expand her research program to include more subjects- this was a very small sample
Which one of the following actions will increase the power of a one-tailed t-test for a mean?
Increase the sample size
Decrease the level of significance
Decrease effect size
Use a two-tailed test
Increase the probability of a type II error
The water diet requires you to drink two cups of water every half hour from the time you get up until you go to bed, but otherwise allows you to eat whatever you like. Four adult volunteers agree to test the diet. They are weighed prior to beginning the diet and after six weeks on the diet. The weight (in pounds) are
Only the distribution of pre-diet weights must be approximately Normal
Only the distribution of differences (after 6 weeks - before) must be approximately Normal
The distribution of both pre-diet weights an six-week weights must be approximately Normal
The distribution of pre-diet weights and the distribution of differences (after 6 weeks - before) must be approximately normal
All three distributions - before diet, after 6 weeks, and the difference - must be approximately normal
What would a Type II error be for this test of the water diet?
Concluding that the diet leads to weight loss when it doesn't
Concluding that the diet leads to weight loss when it really doesn't
Not concluding that the diet leads to weight loss when it does
Not concluding that the diet leads to weight loss when it really doesn't
Drawing a conclusion from this test when the Normality condition has not been satisfied
A city planner is comparing traffic patterns at two different intersections. He randomly selects 12 times between 6 a.m. and 10 p.m., and he and his assistant count the number of cars passing through each intersection during the 10-minute interval that begins at that time. He plans to test the hypothesis that the mean difference in the number of cars passing through the two intersections during each of those 12 times is 0. Which of the following is the appropriate test of the city planner's hypothesis?
two-proportion z-test
Two-sample z-test
matched pairs t-test
two proportion t-test
Two-sample t-test
You are constructing a 90% confidence interval for the difference of means from simple random samples from two independent populations. The sample sizes are n = 6 and n = 14. You draw dot plots of the samples to check the normality condition for two-sample t procedures. Which of the following descriptions of those dot plots would suggest that it is safe to use t-procedures?
I. the dot plot of sample 1 is roughly symmetric, while the dot plot of sample 2 is moderately skewed left. There are no outliers
II. Both dot plots are roughly symmetric. Sample 2 has an outlier
III. Both dot plots are strongly skewed to the right. There are no outliers
I only
II only
I and II
I, II, and III
t-procedures are not recommended in any of these cases
Janice and her cousin Linda are a little competitive bout the relative merits of their homes. One contest they had was to determine who had more rainy days. They found weather records on the internet and each of them randomly selected 60 days from the past 5 years. Janice found that there had been measurable rainfall on 17 of the 60 days she selected for Asheville, and Linda found that there had been measurable rainfall on 12 of the 60 days she selected for Lincoln. They intend to perform a test of significance on their data.
Which of the following best describes what it would mean if Janice and Linda's test resulted in a Type I error
Concluding that there is a difference in the proportion of rainy days in the two cities when there is no difference
Concluding that there is no difference in the proportion of rainy days in the two cities when there is a difference
Choosing the wrong test procedure, such as using a z-test instead of a t-test
Accepting the alternative hypothesis instead of rejecting the null hypothesis
Accepting the null hypothesis instead of rejecting the alternative hypothesis
