Brian Vanecek, VP of Operations at Portland Trust Bank, Is

Multiple Choice

Brian Vanecek, VP of Operations at Portland Trust Bank, is evaluating the service level provided to walk-in customers.Brian would like to minimize the variance of waiting time for these customers, since this would mean each customer received the same level of service.Accordingly, his staff recorded the waiting times for 15 randomly selected walk-in customers, and determined that their mean waiting time was 15 minutes and that the standard deviation was 4 minutes.Assume that waiting time is normally distributed.The 90% confidence interval for the population variance of waiting times is ________.

A) 9.46 to 34.09
B) 56.25 to 64.87
C) 11.05 to 16.03
D) 8.58 to 39.79
E) 12.50 to 42.35