Managing for Quality and Performance Excellence 10th Edition by James Evans ,William Lindsay

Exercise 44

Note: Data sets for many problems in this chapter are available in the Excel workbook C06Data.xlsx on the Student Companion Site. Click on the appropriate worksheet tab as noted in the problem (e.g., Prob. 6-1) to access the data. In addition, the spreadsheet templates illustrated in the chapter are also available to aid in solving many of these problems.
The distribution center manager at Internet distributor Plastik Parts, Inc. wants to find a confidence interval for the average time required for an associate to fill an order for shipment. A sample of 25 orders is taken and the mean time was found to be 9.0 minutes, with a standard deviation of 2.9 minutes. Compute 95 percent and 99 percent confidence intervals. Which one is larger? Explain why.