Question 1

(A)Suppose that Sally wishes to examine a representative subset of these 60 houses that has been stratified by the number of bedrooms.Use Excel to assist her by finding such a stratified sample of size 10 with proportional sample sizes.
(B)Explain how Sally could apply cluster sampling in selecting a sample of size 15 from this frame.
(C)What are the advantages and disadvantages of employing cluster sampling in this case?

Accepted Answer

The answer of (A)Suppose that Sally wishes to examine a...

Question 2

(A)Compute the mean,median,and standard deviation of the annual salaries for the 52 employees in the given frame.
(B)Use Excel to choose a systematic sample of size 13 from the frame of annual salaries.
(C)Compute the mean,median,and standard deviation of the annual salaries for the 13 employees included in your systematic sample in (B)
(D)Compare your statistics in (C)with your computed descriptive measures for the frame in (A).Is your systematic sample representative of the frame with respect to the annual salary variable?
(E)Assume that we wish to stratify these employees by the number of years of post-secondary education,select such a stratified sample of size 15 with approximately proportional sample sizes.
(F)Compute the mean,median,and standard deviation of the annual salaries for the 15 employees included in your stratified sample in (E).
(G)Compare these statistics in (F)with your computed descriptive measures for the frame obtained in (A).Is your stratified sample representative of the frame with respect to the annual salary variable?

Accepted Answer

The answer of (A)Compute the mean,median,and standard deviation of the...

Question 3

(A)What sample size would be required for the production personnel to be approximately 95% sure that their estimate of the average number of defective batteries per box is within 0.3 unit of the true mean? Assume that the best estimate of the population standard deviation (  )is 0.9 defective batteries per box.
(B)How does your answer to (A)change if the production personnel want their estimate to be within 0.5 unit of the actual population mean? Evaluate the tradeoff between required accuracy and sample size requirement for this case and the case in (A).

Accepted Answer

The answer of (A)What sample size would be required for...

Question 4

(A)Using these 50 students as the frame,use Excel to generate a simple random sample of size 10 from this frame.
(B)Compute the mean scores in the frame and the simple random sample you generated in (A).
(C)Compare the mean scores you computed in (B).Is your simple random sample a good representative of the frame? Why or why not?
(D)Using these 50 students as the frame,use Excel to generate a systematic sample of size 10 from this frame.
(E)Compare the mean scores in the frame with that in the systematic sample in (D).What do you conclude?

Accepted Answer

The answer of (A)Using these 50 students as the frame,use...

Question 5

(A)Find the mean and standard deviation of the sampling distribution of the average weekly earnings in the sample.
(B)Find probability that the mean of the sample is less than $445.
(C)Find the probability that the mean of the sample is between $445 and $455.
(D)Find the probability that the mean of the sample is greater than $460.
(E)Explain why the assumption of normality about the distribution of the average weekly earnings for employees was not involved in the answers to (A)through (D).

Accepted Answer

The answer of (A)Find the mean and standard deviation of...

Question 6

A cannery claims that its sardine cans have a net weight of 8 oz.,with a standard deviation of 0.1 oz.You take a simple random sample of 30 cans and encounter a sample mean of 7.85 oz.Are you inclined to believe the claim?

Accepted Answer

The answer of A cannery claims that its sardine cans...

Question 7

(A)What sample size would be required for the auditors to be approximately 95% sure that their estimate of the average savings account balance at this bank is within $150 of the true mean? Assume that their best estimate of the population standard deviation  is $300.
(B)Choose a simple random sample of the size found in (A).
(C)Compute the observed sampling error based on the sample you have drawn from the population.How does the actual sampling error compare to the maximum possible probable absolute error established in (A)? Explain

Accepted Answer

The answer of (A)What sample size would be required for...

Question 8

(A)To assess potential interest in your proposed enterprise,you would like to conduct telephone interviews with a representative subset of the 1000 Internet users.How would you proceed to stratify the given frame of 1000 individuals to choose 50 for telephone interviews? Explain your approach.
(B)Explain how you could apply cluster sampling to obtain a sample size of 50 from this frame.What are the advantages and disadvantages of employing cluster sampling in this case?

Accepted Answer

The answer of (A)To assess potential interest in your proposed...

Question 9

(A)Compute the point estimate of the population mean from the sample above.What is the sampling error in this case? Assume that the population consists of the given 200 customer service times.
(B)Compute the point estimate of the population standard deviation from the sample above.
(C)Should you use the finite population correction (fpc)factor to estimate the standard error of  ? Explain.If your answer is yes,what is the value of the fpc?
(D)Determine a good approximation to the standard error of the mean in this case.

Accepted Answer

The answer of (A)Compute the point estimate of the population...

Question 10

(A)Technically,this process does not yield a random sample of the books in the store.Why not?
(B)How could a truly random sample be obtained?

Accepted Answer

The answer of (A)Technically,this process does not yield a random...

Question 11

(A)Do you think she has obtained a true random sample?
(B)What average price could she report,based on the above sample?
(C)What average price range could she report,based on the above sample?
(D)Do you see any issues with reporting the range calculated for (C)?

Accepted Answer

The answer of (A)Do you think she has obtained a...

Question 12

(A)What sample size would be required for the production personnel to be approximately 95% sure that their estimate of the average number of errors per issue is within 4 errors of the true mean? Assume that the editor's best estimate of the population standard deviation (  )is 10 errors per issue.
(B)How does your answer to (A)change if the editor wants the estimate to be within 3 errors of the actual population mean? Explain the difference in your answers to (A)and (B).

Accepted Answer

The answer of (A)What sample size would be required for...

Quiz 7: Sampling and Sampling Distributions

A cannery claims that its sardine cans have a net weight of 8 oz.,with a standard deviation of 0.1 oz.You take a simple random sample of 30 cans and encounter a sample mean of 7.85 oz.Are you inclined to believe the claim?

(A)Technically,this process does not yield a random sample of the books in the store.Why not? (B)How could a truly random sample be obtained?

(A)Do you think she has obtained a true random sample? (B)What average price could she report,based on the above sample? (C)What average price range could she report,based on the above sample? (D)Do you see any issues with reporting the range calculated for (C)?