Question 1

Bones Brothers & Associates prepare individual tax returns. Over prior years, Bones Brothers has maintained careful records regarding the time to prepare a return. The mean time to prepare a return is 90 minutes and the standard deviation of this distribution is 14 minutes. Suppose 100 returns from this year are selected and analyzed regarding the preparation time. What is the probability that the mean time for the sample of 100 returns is between 88 minutes and 92 minutes?

Accepted Answer

A)  Approximately 1 
B)  0.1664 
C)  0.8336 
D)  0.8472

Question 2

LongLast Inc. produces car batteries. The mean life of these batteries is 60 months. The distribution of the battery life closely follows the normal probability distribution with a standard deviation of eight months. As part of its testing program, LongLast tests a sample of 25 batteries. What is the standard error of the mean?

Accepted Answer

The answer of LongLast Inc. produces car batteries. The mean...

Question 3

Bones Brothers & Associates prepare individual tax returns. Over prior years, Bones Brothers has maintained careful records regarding the time to prepare a return. The mean time to prepare a return is 90 minutes and the standard deviation of this distribution is 14 minutes. Suppose 100 returns from this year are selected and analyzed regarding the preparation time. What is the standard error of the mean?

Accepted Answer

A)  14 minutes 
B)  140 minutes 
C)  1.4 minutes 
D)  90 minutes

Question 4

When doing research, knowing the population mean and other population parameters is essential.

Accepted Answer

A) True 
 B)False

Question 5

The mean of all possible sample means is equal to ____________.

Accepted Answer

A)  The population variance 
B)   
C)  The sample variance 
D)  The population mean

Question 6

LongLast Inc. produces car batteries. The mean life of these batteries is 60 months. The distribution of the battery life closely follows the normal probability distribution with a standard deviation of eight months. As a part of its testing program, LongLast tests a sample of 25 batteries. What proportion of the samples will have a mean useful life between 58 and 62 months?

Accepted Answer

The answer of LongLast Inc. produces car batteries. The mean...

Question 7

How is the central limit theorem helpful when computing probabilities?

Accepted Answer

The answer of How is the central limit theorem helpful...

Question 8

The size of the sampling error is ________.

Accepted Answer

A)  directly related to the sample size-in other words, the larger the sample size, the larger the sampling error 
B)  directly related to the population mean-in other words, the larger the mean, the larger the sampling error 
C)  inversely related to the sample size-in other words, the larger the sample size, the smaller the sampling error 
D)  inversely related to the population standard deviation-in other words, the smaller the standard deviation, the larger the sampling error

Question 9

A population consists of 14 values. How many samples of size five are possible?

Accepted Answer

The answer of A population consists of 14 values. How...

Question 10

The following data was collected from a simple random sample of a population of college freshmen. It represents their ages on the first day of the fall semester. 17 21 19 18 18 19
The point estimates of the population mean and standard deviation are:

Accepted Answer

A)  18 and 1.75. 
B)  19 and 1.78. 
C)  17.67 and 1.63. 
D)  18.67 and 1.36.

Question 11

For a sampling distribution of the means, about ________% of the means would be between ±1.96 standard deviations.

Accepted Answer

The answer of For a sampling distribution of the means,...

Question 12

The central limit theorem states that if the sample size, n, is sufficiently large, the sampling distribution of the means will be approximately normal, even when the population is skewed or uniform.

Accepted Answer

A) True 
 B)False

Question 13

The American Auto Association reports that the mean price per gallon of regular gasoline is $3.10, with a population standard deviation of $0.20. Assume a random sample of 16 gasoline stations is selected and their mean cost for regular gasoline is computed. What is the standard error of the mean in this experiment?

Accepted Answer

The answer of The American Auto Association reports that the...

Question 14

A characteristic of a population is called a ______________.

Accepted Answer

The answer of A characteristic of a population is called...

Question 15

In stratified random sampling, a population is divided into strata using naturally occurring geographic or other boundaries. Then, strata are randomly selected and a random sample is collected from each strata.

Accepted Answer

A) True 
 B)False

Question 16

To study the population of consumer perceptions of new technology, sampling of the population is preferred over surveying the population because _________.

Accepted Answer

A)  sampling is more accurate 
B)  we can compute z-scores 
C)  it is quicker 
D)  sampling methods are simple

Question 17

Auditors may select every 20^th file starting with the 5^th file in the top drawer. Then, file numbers 25, 45, 65, 85, . . . are selected. This type of sampling is called ___________.

Accepted Answer

The answer of Auditors may select every 20^th file starting...

Question 18

The Intelligence Quotient (IQ) test scores for adults are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability we could select a sample of 50 adults and find that the mean of this sample is between 98 and 103?

Accepted Answer

A)  0.3264 
B)  0.9428 
C)  0.4702 
D)  0.7471

Question 19

If every k^th item in the population sequence is selected, you should use the __________________ sampling method.

Accepted Answer

The answer of If every k^th item in the population...

Question 20

For a sampling distribution of the means, _______% of the means would be between ±2.58 standard deviations.

Accepted Answer

The answer of For a sampling distribution of the means,...

Exam 8: Sampling Methods and the Central Limit Theorem

When doing research, knowing the population mean and other population parameters is essential.

The mean of all possible sample means is equal to ____________.

How is the central limit theorem helpful when computing probabilities?

The size of the sampling error is ________.

A population consists of 14 values. How many samples of size five are possible?

The following data was collected from a simple random sample of a population of college freshmen. It represents their ages on the first day of the fall semester. 17 21 19 18 18 19 The point estimates of the population mean and standard deviation are:

For a sampling distribution of the means, about ________% of the means would be between ±1.96 standard deviations.

The central limit theorem states that if the sample size, n, is sufficiently large, the sampling distribution of the means will be approximately normal, even when the population is skewed or uniform.

A characteristic of a population is called a ______________.

In stratified random sampling, a population is divided into strata using naturally occurring geographic or other boundaries. Then, strata are randomly selected and a random sample is collected from each strata.

To study the population of consumer perceptions of new technology, sampling of the population is preferred over surveying the population because _________.

Auditors may select every 20th file starting with the 5th file in the top drawer. Then, file numbers 25, 45, 65, 85, . . . are selected. This type of sampling is called ___________.

The Intelligence Quotient (IQ) test scores for adults are normally distributed with a mean of 100 and a standard deviation of 15. What is the probability we could select a sample of 50 adults and find that the mean of this sample is between 98 and 103?

If every kth item in the population sequence is selected, you should use the __________________ sampling method.

For a sampling distribution of the means, _______% of the means would be between ±2.58 standard deviations.

Auditors may select every 20^th file starting with the 5^th file in the top drawer. Then, file numbers 25, 45, 65, 85, . . . are selected. This type of sampling is called ___________.

If every k^th item in the population sequence is selected, you should use the __________________ sampling method.