The correct answer for each question is indicated by a .

1

When estimating population parameters, a point estimate is:

A)

a range of possible values for a population parameter.

B)

always equal to a population value.

C)

a statistic that estimates a population parameter.

D)

the population mean.

2

A characteristic of all confidence intervals is that:

A)

a confidence interval always includes the population parameter.

B)

a confidence interval always increases in width as the sample size is increased.

C)

a confidence interval cannot include a value of 0.

D)

a confidence interval always increases in width as the level of confidence increases.

3

If we wish to decrease the width (increase the precision) of a confidence interval, we would:

A)

increase the size of the sample.

B)

reduce the size of the population.

C)

raise the level of confidence.

D)

compute the mean.

4

We wish to develop a confidence interval for the population mean. The population standard deviation is known. We have a sample of 40 observations. We decide to use the 92 percent level of confidence. The appropriate value of z is:

A)

1.96.

B)

1.65.

C)

2.58.

D)

1.75.

5

Which of the following statements is a characteristic of the t distribution?

A)

It is a continuous distribution.

B)

It has a mean of 0.

C)

It is symmetrical.

D)

All of the above.

6

We wish to develop a confidence interval for the population mean. The population follows the normal distribution, the standard deviation of the population is 3, and we have a sample of 10 observations. We decide to use the 90 percent level of confidence. The appropriate statistic for the level of confidence is:

A)

z = 1.645.

B)

z = 1.960.

C)

t = 1.833.

D)

t = 2.262.

7

The fraction of a sample possessing a certain trait is called a:

A)

population.

B)

mean.

C)

confidence interval.

D)

proportion.

8

To develop a confidence interval for a proportion:

A)

we approximate the binomial distribution with a normal distribution.

B)

the sample size should be at least 100.

C)

p should be less than .05.

D)

we use the t statistic.

9

We wish to compute an interval estimate of the population proportion. We want to be 95 percent confident of our results and we want the estimate to be within .01 of the population parameter. No estimate of the population proportion is available. What value should we use for p?

A)

1.96

B)

.01

C)

.50

D)

Any value between zero and one

10

We wish to develop a confidence interval for the population mean. The population follows the normal distribution and the population standard deviation is 3. We collect a random sample of 10 observations. We decide to use the 90 percent level of confidence. The margin of error for the confidence interval is:

A)

± 1.645.

B)

± 1.565.

C)

± 2.262.

D)

± 2.146.

11

We wish to develop a confidence interval for the population mean. The population follows the normal distribution. We collect a random sample of 10 observations and the sample standard deviation is 3. We decide to use the 95 percent level of confidence. The margin of error for the confidence interval is:

A)

± 1.859.

B)

± 1.960.

C)

± 2.262.

D)

± 2.146.

12

To conduct a research project on college student income, the number of students to sample needs to be calculated. To estimate the mean population income, we decide to use a 95% level of confidence. The desired margin of error is plus or minus $500. The standard deviation from other studies of student income is $1000. What sample size should be used?

A)

4

B)

16

C)

11

D)

1

13

To conduct a research project on college student income, the number of students to sample needs to be calculated. To estimate the mean population income, we decide to use a 99% level of confidence. The desired margin of error is plus or minus $200. The standard deviation from other studies of student income is $1500. What sample size should be used?

A)

20

B)

1

C)

217

D)

374

14

To conduct a research project on whether college students purchase textbooks, the number of students to sample needs to be calculated. To estimate the population proportion, we decide to use a 95% level of confidence. The desired margin of error is plus or minus 0.10. There is no prior estimate of the population proportion. What sample size should be used?

A)

97

B)

5

C)

25

D)

68

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