Question 1

Doubling the size of the sample will

Accepted Answer

A) reduce the standard error of the mean to one-half its current value 
B) reduce the standard error of the mean to approximately 70% of its current value 
C) have no effect on the standard error of the mean 
D) double the standard error of the mean

Question 2

A sample of 10 members of a video club provides the following data on number of videos they own. Use Excel to answer the questions that follow the data.  
a.What is the point estimate for the mean number of videos owned by all video club members?
b.Determine the point estimate for the standard deviation of the population.

Accepted Answer

The answer of A sample of 10 members of a...

Question 3

Stratified random sampling is a method of selecting a sample in which

Accepted Answer

A) the sample is first divided into groups, and then random samples are taken from each group 
B) various strata are selected from the sample 
C) the population is first divided into groups, and then random samples are drawn from each group 
D) None of the alternative answers is correct.

Question 4

Candidate A is running for president of the student government at a large university. The proportion of voters who favor the candidate is 0.8. A simple random sample of 100 voters is taken.
a.What are the expected value, standard deviation, and shape of the sampling distribution of ?
b.What is the probability that the number of voters in the sample who will not favor Candidate A will be between 26 and 30?
c.What is the probability that the number of voters in the sample who will not favor Candidate A will be more than 16?

Accepted Answer

The answer of Candidate A is running for president of...

Question 5

Missy Walters owns a mail-order business specializing in baby clothes. Missy is confident the dollar amounts of all her orders are normally distributed or nearly so. Assume she knows the mean and standard deviation are $249 and $46, respectively, for all orders she receives.
a. Describe the sampling distribution of  , where  is the mean dollar-amount of an order for a sample of 10 orders. 
b. What is the probability that a simple random sample of 30 orders will provide an estimate of the population mean dollar-amount of an order that is within plus or minus $10 of the actual population mean?
c. What happens to the sampling distribution of  when the sample size is increased from 30 to 90? With a sample size of 90, what is the probability that  will be between $239 and $259?

Accepted Answer

The answer of Missy Walters owns a mail-order business specializing...

Question 6

There are 500 employees in a firm, 45% are female. A sample of 60 employees is selected randomly.
a.Determine the standard error of the proportion.
b.What is the probability that the sample proportion of females is between 0.40 and 0.55?

Accepted Answer

The answer of There are 500 employees in a firm,...

Question 7

Thirty percent of a magazine's subscribers are female. A random sample of 50 subscribers is taken. Answer the following questions using Excel.
a.What is the probability that the proportion of females from this sample is at most 0.25?
b.What is the probability that the proportion of females from this sample is between 0.22 and 0.28?
c.What is the probability that the proportion of females from this sample is within .03 of the population proportion?

Accepted Answer

The answer of Thirty percent of a magazine's subscribers are...

Question 8

Random samples of size 525 are taken from a process (an infinite population) whose population proportion is 0.3. The standard deviation of the sample proportions (i.e., the standard error of the proportion) is

Accepted Answer

A) 0.0004 
B) 0.2100 
C) 0.3000 
D) 0.0200

Question 9

A simple random sample of size n from a finite population of size N is a sample selected such that each possible sample of size

Accepted Answer

A) N has the same probability of being selected 
B) n has a probability of 0.5 of being selected 
C) n has a probability of 0.1 of being selected 
D) n has the same probability of being selected

Question 10

The price of a particular brand of jeans has a mean of $37.99 and a standard deviation of $7. A sample of 49 pairs of jeans is selected. Use Excel to answer the following questions.
a.What is the probability that the sample of jeans will have a mean price less than $40?
b.What is the probability that the sample of jeans will have a mean price between $38 and $39?
c.What is the probability that the sample of jeans will have a mean price within $3 of the population mean?

Accepted Answer

The answer of The price of a particular brand of...

Question 11

Exhibit 7-3
The following information was collected from a simple random sample of a population.
 
-Refer to Exhibit 7-3. The point estimate of the mean of the population is

Accepted Answer

A) 18.0 
B) 19.6 
C) 108 
D) sixteen, since 16 is the smallest value in the sample

Question 12

In a local university, 10% of the students live in the dormitories. A random sample of 100 students is selected for a particular study.
a.What is the probability that the sample proportion of students living in the dormitories is between 0.172 and 0.178?
b.What is the probability that the sample proportion of students living in the dormitories is greater than 0.025?

Accepted Answer

The answer of In a local university, 10% of the...

Question 13

The standard deviation of all possible  values is called the

Accepted Answer

A) standard error of proportion 
B) standard error of the mean 
C) mean deviation 
D) central variation

Question 14

A subset of a population selected to represent the population is a

Accepted Answer

A) subset 
B) sample 
C) small population 
D) None of the alternative answers is correct.

Question 15

It is impossible to construct a frame for a

Accepted Answer

A) finite population 
B) infinite population 
C) target population 
D) sampled population

Question 16

Exhibit 7-1
The following data was collected from a simple random sample from a process (an infinite population).
 
-Refer to Exhibit 7-1. The point estimate of the population mean

Accepted Answer

A) is 5 
B) is 14 
C) is 4 
D) cannot be determined because the population is infinite

Question 17

From a population of 200 elements, the standard deviation is known to be 14. A sample of 49 elements is selected. It is determined that the sample mean is 56. The standard error of the mean is

Accepted Answer

A) 3 
B) 2 
C) greater than 2 
D) less than 2

Question 18

The life expectancy in the United States is 75 with a standard deviation of 7 years. A random sample of 49 individuals is selected.
a.What is the probability that the sample mean will be larger than 77 years?
b.What is the probability that the sample mean will be less than 72.7 years?
c.What is the probability that the sample mean will be between 73.5 and 76 years?
d.What is the probability that the sample mean will be between 72 and 74 years?
e.What is the probability that the sample mean will be larger than 73.46 years?

Accepted Answer

The answer of The life expectancy in the United States...

Question 19

Exhibit 7-5
Random samples of size 17 are taken from a population that has 200 elements, a mean of 36, and a standard deviation of 8.
-Refer to Exhibit 7-5. Which of the following best describes the form of the sampling distribution of the sample mean for this situation?

Accepted Answer

A) Approximately normal because the sample size is small relative to the population size. 
B) Approximately normal because of the central limit theorem. 
C) exactly normal 
D) None of the alternative answers is correct.

Question 20

As a general rule, the sampling distribution of the sample proportions can be approximated by a normal probability distribution whenever

Accepted Answer

A) np F1F1F1S1F1F1F10 5 
B) n(1 F1F1F1S1F1F1F10 p) F1F1F1S1F1F1F10 5 
C) n F1F1F1S1F1F1F10 30 
D) Both np F1F1F1S1F1F1F10 5 and n(1 F1F1F1S1F1F1F10 p) F1F1F1S1F1F1F10 5 are true.

Exam 7: Sampling and Sampling Distributions

Doubling the size of the sample will

Stratified random sampling is a method of selecting a sample in which

There are 500 employees in a firm, 45% are female. A sample of 60 employees is selected randomly. a.Determine the standard error of the proportion. b.What is the probability that the sample proportion of females is between 0.40 and 0.55?

Random samples of size 525 are taken from a process (an infinite population) whose population proportion is 0.3. The standard deviation of the sample proportions (i.e., the standard error of the proportion) is

A simple random sample of size n from a finite population of size N is a sample selected such that each possible sample of size

Exhibit 7-3 The following information was collected from a simple random sample of a population. -Refer to Exhibit 7-3. The point estimate of the mean of the population is

The standard deviation of all possible values is called the

A subset of a population selected to represent the population is a

It is impossible to construct a frame for a

Exhibit 7-1 The following data was collected from a simple random sample from a process (an infinite population) . -Refer to Exhibit 7-1. The point estimate of the population mean

From a population of 200 elements, the standard deviation is known to be 14. A sample of 49 elements is selected. It is determined that the sample mean is 56. The standard error of the mean is

Exhibit 7-5 Random samples of size 17 are taken from a population that has 200 elements, a mean of 36, and a standard deviation of 8. -Refer to Exhibit 7-5. Which of the following best describes the form of the sampling distribution of the sample mean for this situation?

As a general rule, the sampling distribution of the sample proportions can be approximated by a normal probability distribution whenever