Exam 17: Additional Topics in Sampling

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A supermarket chain has 25 stores in the North,30 in the South,50 in the Midwest,and 35 in the West.Using a proportional allocation of a random sample of 30% of the outlets,the manager records the following means and standard deviations. -Quota sampling is an example of a:

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: Of the 1400 colleges in the United States,370 have two-year schools and 1030 have four-year schools.In a random sample of 40 two-year schools,it was found that 10 of the schools do not have any faculty holding a Ph.D.degree.In an independent random sample of 60 four-year schools,it was found that only 6 of the schools do not have any faculty holding a Ph.D.degree. -Find an estimate of the proportion of all the colleges that do not have any faculty holding a Ph.D.degree using an unbiased estimation procedure.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: The U.S.Senate has 100 members.62 senators' offices obtained certain information from the individuals responsible for managing correspondence.Of these,40 specified a minimum number of letters that must be received on an issue before a form letter in response is created. -Assume these observations constitute a random sample from the population,and find a 90% confidence interval for the proportion of all senators' offices with this policy.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: The faculty advisor at a local business school is interested in determining the monthly expenditures on stationeries for students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class. -Find a 98% confidence interval for the mean monthly expenditures.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: An auditor,examining a total of 800 accounts receivable by a corporation,selected a random sample of 60 accounts.The sample mean is $130.54 and the sample standard deviation is $42.56. -Find a 95% confidence interval for the total amount of the 800 accounts receivable.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A sales representative has 398 accounts.From a random sample of 56 of these accounts,she found that the average yearly order was $1,239 with a standard deviation of $73,and that 27 had placed an order within the last 30 days. -Estimate the proportion of all accounts that placed an order within the last 30 days.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A supermarket chain has 25 stores in the North,30 in the South,50 in the Midwest,and 35 in the West.Using a proportional allocation of a random sample of 30% of the outlets,the manager records the following means and standard deviations. -Estimate the population mean.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: The mean household income,in dollars,must be estimated for a town that is divided into three districts.The relevant information is shown in the table. A 95% confidence interval for the population mean that extends $550 on each side of the sample estimate is required. -Determine how many sample observations are needed under the proportional allocation scheme.

Stratified random sampling involves selecting a simple random sample from each of a given number of subpopulations,called strata.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: The faculty advisor for the marketing society at a local business school is interested in determining the monthly expenditures on entertainment for marketing students.The advisor samples some students from each class and computes the sample mean and standard deviation for each class. -Find a 95% confidence interval for the mean monthly expenditures.