Free Printable 8.1 - 8.2 Review

1.

The general form of a confidence interval is

a)

point estimate x 2

b)

point estimate + margin of error

c)

point estimate - margin of error

d)

point estimate +/- margin of error

2.

A confidence interval gives all plausible values of the population parameter you are trying to estimate

a)

TRUE

b)

FALSE

c)

I HAVE NO IDEA

3.

Given a confidence interval, how do you determine the value of the point estimate?

a)

Find the middle of the interval - (lower value + upper value)/2.

b)

Find the range of the interval and divide by 2.

c)

Use the lower end of the interval.

d)

You can't determine the point estimate from the confidence interval.

4.

If a proposed value of the population parameter is not captured in the confidence interval, there is convincing evidence that that proposed value is incorrect.

a)

TRUE

b)

FALSE

5.

Polling organizations regularly survey US adults to ask if they approve of the job the president is doing. on the day of the 2014 midterm elections, the 95% confidence interval for the proportion of all US adults that approved of President Obama's job performance was 0.39 to 0.45. Interpret the confidence interval.

a)

The probability that the true proportion of all US adults that approve of Obama's job performance is between 0.39 to 0.45.

b)

The probability that the true proportion of all US adults that approve of Obama's job performance is 95%.

c)

We are 95% confident that the interval from 0.39 to 0.45 captures the true proportion of all US adults who approve of Obama's job performance.

d)

We are 95% confident that the interval from 0.39 to 0.45 captures the sample proportion of all US adults who approve of Obama's job performance.

6.

Polling organizations regularly survey US adults to ask if they approve of the job the president is doing. on the day of the 2014 midterm elections, the 95% confidence interval for the proportion of all US adults that approved of President Obama's job performance was 0.39 to 0.45. Calculate the point estimate.

a)

0.39

b)

0.45

c)

0.42

d)

0.06

e)

0.03

7.

Polling organizations regularly survey US adults to ask if they approve of the job the president is doing. on the day of the 2014 midterm elections, the 95% confidence interval for the proportion of all US adults that approved of President Obama's job performance was 0.39 to 0.45. Calculate the margin of error.

a)

0.39

b)

0.45

c)

0.42

d)

0.06

e)

0.03

8.

Polling organizations regularly survey US adults to ask if they approve of the job the president is doing. on the day of the 2014 midterm elections, the 95% confidence interval for the proportion of all US adults that approved of President Obama's job performance was 0.39 to 0.45.

Based on the confidence interval, it is plausible that on the day of the 2014 midterm elections, a majority of US adults approved of Obama's job performance.

a)

True

b)

False

9.

A local pizza shop claims that they deliver pizzas in under 30 minutes on average. You randomly select 12 different times during the next week and order a pizza to be delivered to your home. The 95% confidence interval for the mean delivery time is 26.8 minutes to 41.0 minutes. Interpret the confidence interval.

a)

The probability that the true mean delivery time is 30 minutes is 95%.

b)

The probability is 95% that the true true mean delivery time is between 26.8 and 41 minutes.

c)

We are 95% confident that the interval from 26.8 to 41 minutes captures the sample mean delivery time.

d)

We are 95% confident that the interval from 26.8 to 41 minutes captures the true mean delivery time.

10.

A local pizza shop claims that they deliver pizzas in 30 minutes or less. The 95% confidence interval obtained from a random sample of 12 deliveries is [26.8,41.0].

Calculate the point estimate used to create this interval.

a)

7.1 minutes

b)

13.4 minutes

c)

33.9 minutes

d)

30.7 minutes

11.

A local pizza shop claims that they deliver pizzas in 30 minutes or less. The 95% confidence interval obtained from a random sample of 12 deliveries is [26.8,41.0].

Calculate the margin of error used to create this interval.

a)

7.1 minutes

b)

13.4 minutes

c)

33.9 minutes

d)

30.7 minutes

12.

A local pizza shop claims that they deliver pizzas in 30 minutes or less. The 95% confidence interval obtained from a random sample of 12 deliveries is [26.8,41.0].

Is there evidence to suggest that the stated mean delivery time is 30 minutes or less is incorrect?

a)

No. There are values in the interval that are 30 or less, so it is plausible the the pizza shop is making a valid claim.

b)

Yes. There are values higher than 30 in the interval which means that the pizza shop is delivering pizzas in more time than 30 minutes.

c)

No. The interval does not contain 30, so this value must be incorrect.

13.

A magazine reported that 66% of dog owners greet their dog before their spouse of children when they arrive home.

A random sample of 40 dog owners was obtained and a 95% confidence interval was calculated as [0.68, 0.78].

Calculate the point estimate that was used to create this interval

a)

78%

b)

5%

c)

73%

d)

66%

14.

A magazine reported that 66% of dog owners greet their dog before their spouse of children when they arrive home.

A random sample of 40 dog owners was obtained and a 95% confidence interval was calculated as [0.68, 0.78].

Calculate the margin of error that was used to create this interval

a)

78%

b)

5%

c)

73%

d)

66%

15.

A magazine reported that 66% of dog owners greet their dog before their spouse of children when they arrive home.

A random sample of 40 dog owners was obtained and a 95% confidence interval was calculated as [0.68, 0.78].

Is there evidence to suggest that true proportion of dog owner who greet their dog first is not 66%?

a)

No, It is plausible that 66% is correct since it is in the interval.

b)

Yes. Since 66% is not a plausible value of the population parameter, there is evidence that the magazine is incorrect.

c)

I can't tell whether or not 66% is incorrect with any certainty.

16.

Determine whether the action would increase or decrease the margin of error:

Increase the sample size

a)

Margin of error increases

b)

Margin of error decreases

17.

What does SRS stand for?

a)

Simple Random Sample

b)

Survey Random Samples

c)

Simple Random Survey

d)

Sample Random Surveys

18.

How do we reduce bias?

a)

Increase variability

b)

Increase randomness

c)

Decrease randomness

d)

Decrease variability

19.

The parameter is a number describing the:

a)

population

b)

sample

c)

survey

d)

percent

20.

The statistic is a number describing the:

a)

population

b)

sample

c)

survey

d)

percent

21.

To reduce the variability of estimates from a simple random sample, you should

a)

use a smaller sample.

b)

increase the bias.

c)

use a count, not a percent.

d)

use a larger sample.

22.

A sample is taken of 200 people. The number of people who own a dog was 80.
What is the sample proportion?

a)

80

b)

0.8

c)

0.4

d)

35%

23.

What is the effect of increasing the confidence level on the margin of error, assuming the sample size remains constant?

a)

Increases the margin of error

b)

Decreases the margin of error

c)

Does not affect the margin of error

d)

Initially increases, then decreases the margin of error

24.

How does increasing the sample size affect the margin of error, assuming the confidence level remains the same?

a)

Increases the margin of error

b)

Decreases the margin of error

c)

Does not affect the margin of error

d)

Initially decreases, then increases the margin of error

25.

If the observed sample proportion is 0.55 and the margin of error is 0.05, what is the confidence interval?

a)

(0.50, 0.60)

b)

(0.45, 0.65)

c)

(0.55, 0.60)

d)

(0.50, 0.55)

26.

HSHS has about 1432 students this year. A random sample of 100 HSHS students found that 53 of them were in possession of a pencil. What is the point estimate for this sample?

a)

0.53

b)

50

c)

100

d)

1432

27.

Which of the following actions would produce a confidence interval with a smaller width assuming all other contingencies remained constant?

a)

Using a higher confidence level

b)

Using a lower confidence level

28.

In a survey about the number of people that favor the current mayor resulted in the confidence interval below.

A 99% confidence interval for p is (0.652, 0.868). Interpret this interval.

a)

99% of the time the true proportion of people who favor the mayor is between 65.2% and 86.6%.

b)

The probability that the population proportion of people that favor the mayor is between 65.2% and 86.6% is 99%.

c)

Based on this sample, I am 99% confident that the true proportion of people that favor the mayor is between 65.2% and 86.6%.

29.

For a sample, the 95% confidence interval is (0.202, 0.482).

What is the point estimate, p̂, of this sample?

a)

0.28

b)

0.14

c)

0.342

d)

0.684

30.

Which confidence would result in a larger margin of error (assuming nothing else changed), 91% or 97%?

a)

97%

b)

91%

c)

They have the same margin of error.

31.

Increasing the sample size __________ the margin of error.

a)

increases

b)

decreases

c)

does not affect

32.

The amount added and subtracted to the statistic.

a)

Margin of Error

b)

Point Estimator

c)

Statistic

d)

Population

33.

What is the margin of error for the interval (6.8, 12.9)?

a)

9.85

b)

3.05

c)

3.50

d)

6.8

34.

Increasing the sample size makes the confidence interval

a)

wider.

b)

narrower.

c)

does not affect the interval.

35.

Increasing the confidence level makes the confidence interval

a)

wider.

b)

narrower.

c)

does not affect the interval.

36.

Decreasing the confidence level makes the confidence interval

a)

wider.

b)

narrower.

c)

does not affect the interval.

37.

In a survey about the number of people that favor the current mayor resulted in the confidence interval below.

A 99% confidence interval for p is (0.652, 0.868). Interpret this LEVEL.

a)

99% of all intervals using this method will capture the true proportion of people that favor the mayor.

b)

99% of the time, the interval will capture the true proportion of people who favor the mayor.

38.

Increasing the confidence level from 90% to 95% makes the margin of error

a)

smaller.

b)

larger.

c)

does not affect the interval.

39.

Decreasing the confidence level from 98% to 95% makes the margin of error

a)

smaller.

b)

larger.

c)

does not affect the interval.

40.

Which of the following changes to a study would result in a narrower confidence interval?

a)

increasing the confidence level, increasing the sample size

b)

decreasing the confidence level, decreasing the sample size

c)

increasing the confidence level, decreasing the sample size

d)

decreasing the confidence level, increasing the sample size.

8.1 - 8.2 Review

Total questions: 40

Worksheet time: 1hrs 16mins

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