A manufacturing company’s quality control personnel have recorded the proportion of defective items for each of 500 monthly shipments of one of the computer components that the company produces. The data are in the file P2_2.XLS. The quality control department manager does not have sufficient time to review all of these data. Rather, she would like to examine the proportions of defective items for a sample of these shipments.

a. Use Excel to generate a simple random sample of size 25 from the given frame.

b. Compute a point estimate of the population mean from the sample selected in part a. What is the sampling error in this case? Assume that the population consists of the proportion of defective items for each of the given 500 monthly shipments.

c. Determine a good approximation to the standard error of the mean in this case.

d. Repeat parts b and c after generating a simple random sample of size 50 from the given frame.