Question 1

The procurement manager for a large company wishes to estimate the proportion of parts from a supplier that are defective.She has selected a random sample of n = 200 incoming parts and has found 11 to be defective.Based on a 95 percent confidence level,the upper and lower limits for the confidence interval estimate are approximately 0.0234 to 0.0866.

Accepted Answer

A) True 
 B)False

Question 2

If a pilot sample of n = 40 items has been used as a first step in determining a required sample size of n = 360,the decision maker can go ahead and use these 40 and take a sample of only 320 more items.

Accepted Answer

A) True 
 B)False

Question 3

The U.S.Post Office is interested in estimating the mean weight of packages shipped using the overnight service.They plan to sample 300 packages.A pilot sample taken last year showed that the standard deviation in weight was about 0.15 pounds.If they are interested in an estimate that has 95 percent confidence,what margin of error can they expect?

Accepted Answer

A) Approximately 0.017 pounds 
B) About 0.0003 pounds 
C) About 1.96 
D) Can't be determined without knowing the population mean.

Question 4

If we are interested in estimating the population mean based on a sample from a population for which we know neither the mean nor the standard deviation,the critical value will be a t value from the t-distribution.

Accepted Answer

A) True 
 B)False

Question 5

A random sample of 100 people was selected from a population of customers at a local bank.The mean age of these customers was 40.If the population standard deviation is thought to be 5 years,the margin of error for a 95 percent confidence interval estimate is .98 years.

Accepted Answer

A) True 
 B)False

Exam 8: Estimating Single Population Parameters

If a pilot sample of n = 40 items has been used as a first step in determining a required sample size of n = 360,the decision maker can go ahead and use these 40 and take a sample of only 320 more items.

If we are interested in estimating the population mean based on a sample from a population for which we know neither the mean nor the standard deviation,the critical value will be a t value from the t-distribution.

A random sample of 100 people was selected from a population of customers at a local bank.The mean age of these customers was 40.If the population standard deviation is thought to be 5 years,the margin of error for a 95 percent confidence interval estimate is .98 years.