The correct answer for each question is indicated by a .

1

A simple random sample assures that:

A)

all items in a population have an equal probability of selection.

B)

the sample will be at least 30 observations.

C)

the sample size will be equal to the population size, N.

D)

the sample will be biased.

2

Sampling is often preferred to surveying a population because:

A)

surveying a population can be very expensive.

B)

it can be physically impossible to find all the items in the population.

C)

sample estimates can be very accurate.

D)

All of the above are reasons for sampling.

3

Which of the following is a method of probability sampling?

A)

Simple random sampling

B)

Systematic sampling

C)

Stratified sampling

D)

All of the above are methods of probability sampling.

4

In a simple random sample:

A)

every k^{th} item is selected to be in the sample.

B)

every item has a chance to be in the sample.

C)

every item has the same chance to be in the sample.

D)

only 10 items are selected.

5

Suppose a population consisted of 20 items. How many different samples of n = 3 are possible?

A)

6840

B)

1140

C)

20

D)

120

6

The difference between the sample mean and the population mean is called the:

A)

population deviation.

B)

population standard deviation.

C)

standard error of the mean.

D)

sampling error.

7

For the sampling distribution of sample means, what is the relationship between the population mean and the mean of all possible sample means of size 25?

A)

They are equal.

B)

They are not equal.

C)

They are different by one standard error of the mean.

D)

They are both normally distributed.

8

When comparing the variances of a population distribution and a sampling distribution of means from the population the:

A)

variances are equal.

B)

population variance is smaller than the sampling distribution variance.

C)

population variance is larger than the sampling distribution variance.

D)

variances have the same degrees of freedom.

9

The standard error of the mean is:

A)

the standard deviation of the sampling distribution of sample means.

B)

always normally distributed.

C)

sometimes less than 0.

D)

the variance squared.

10

A population distribution is normal with a mean of 18 and standard deviation of 4. A sample of 16 observations is selected and a sample mean computed. What is the probability that the sample mean is more than 18?

A)

0.5

B)

1.0

C)

0.0

D)

18

11

A population distribution is normal with a mean of 18 and standard deviation of 4. A sample of 16 observations is selected and a sample mean computed. What is the probability that the sample mean is more than 20?

A)

0.500

B)

0.4772

C)

0.0

D)

0.0228

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