Managing for Quality and Performance Excellence 9th Edition by James Evans,William Lindsay

Exercise 15

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.
Rabbitfoot Community Bank makes a large number of home equity loans each year. The vice president of loan administration wishes to determine if their time for paperwork processing is lower than the average time of their top competitor. A sample of 30 loans taken at Rabbitfoot Bank yielded a mean of 38.10 minutes and a standard deviation of 2.58 minutes (see the data in the Ch06Data Excel workbook). Data obtained from competitor of 36 applications indicates that the average time for processing an application is 39.48 minutes, with a standard deviation of 2.48 minutes.
a. Verify the calculation of the mean, standard deviation, and variance for each set of data using the Descriptive Statistics tool.
b. Test the null hypothesis that his bank's processing time is greater than or equal to the competitor's average, versus the alternative hypothesis that the bank's time is less than the competitor at the 5 percent significance level. Use the z-Test: Two Sample Assuming Equal Variances from the Data Analysis menu in Excel.