1 of20

Decreasing the sample size, while holding the confidence level the same, will do what to the length of your confidence interval?

	make it bigger
	make it smaller
	it will stay the same
	cannot be determined from the given information

Question

2 of20

Decreasing the confidence level, while holding the sample size the same, will do what to the length of your confidence interval?

	make it bigger
	make it smaller
	it will stay the same
	cannot be determined from the given information

Question

3 of20

All else being equal, the larger the sample size

	the wider the confidence interval
	the narrower the confidence interval

Question

4 of20

Which of the below is not part of a confidence interval?

	a confidence level
	a parameter
	a margin of error
	a statistic

Question

5 of20

In constructing a confidence interval, x is used as an estimate of the population mean.

	True
	False

Question

6 of20

x Erepresents

	the confidence level
	the confidence interval
	sampling error
	random error of measurement

Question

7 of20

A 95% confidence interval for the mean number of televisions per American household is (1.15, 4.20).

	The probability that is between 1.15 and 4.20 is .95.
	We are 95% confident that the true mean number of televisions per American household is between 1.15 and 4.20.
	95% of all samples should have x-bars between 1.15 and 4.20.
	95% of all American households have between 1.15 and 4.20 televisions.

Question

8 of20

If you increase the sample size and confidence level at the same time, what will happen to the length of your confidence interval?

	make it bigger
	make it smaller
	it will stay the same
	cannot be determined from the given information

Question

9 of20

In constructing a confidence interval,sis used as an estimate of the population variance.

	True
	False

Question

10 of20

In calculations of the confidence interval for a mean with known population , z_c(SE)represents

	the alpha level
	the confidence level
	the margin of error

Question

11 of20

The critical value used for a 99% confidence interval for a sample mean when the population standard deviation is known is 2.58.

	True
	False

Question

12 of20

In calculations of the confidence interval for a mean with known population , the standard error is calculated as

	x E

Question

13 of20

The formula used to calculate at-score is the same as the formula for a z-score.

	True
	False

Question

14 of20

The 95% confidence interval for an exam has a sample mean of 72 and a margin of error of 7. What is the lower bound for the interval?

	7
	65
	72
	79

Question

15 of20

What is thet-score associated with 95% confidence and a sample size of 15?

	1.761
	1.753
	2.145
	2.131

Question

16 of20

Thet-distribution has which of the following characteristics?

	It is bell shaped, symmetric and centered around zero.
	It has heavier tails than the normal distribution.
	The exact shape depends on its degrees of freedom.
	All the above are characteristics of thet-distribution.

Question

17 of20

A nutrition study based on a sample of 20 cupcakes found the confidence interval for the mean number of calories to be (150, 350). Which is the correct interpretation of the 90% confidence interval?

	We are 90% confident that the true mean calorie content can be found with a sample of 150 to 350 cupcakes.
	We are 90% confident that a sample of 20 cupcakes will find 250 calories per cupcake.
	We are 90% confident that the true mean calorie content in these cupcakes is between 150 and 350 calories.
	None of these are correct.

Question

18 of20

When the population standard deviation is unknown we usesas an estimate of .

	True
	False

Question

19 of20

Which of the following sources of error is included in the margin of error?

	voluntary response
	some of the subjects did not understand the questions
	undercoverage of the topic
	chance variation in choosing a random sample

Question

20 of20

A researcher is deciding what level of confidence to use for a public opinion poll. What would you expect to happen to the margin of error as a result of changing from 90% to 95% for the confidence level?

	margin of error becomes larger
	margin of error becomes less
	margin of error stays the same
	cannot answer without more information