A bank with branches located in a commercial district of a city and in a residential area has the business objective of developing an improved process for serving customers during the noon-to-1 P.M. lunch period. Management decides to first study the waiting time in the current process. The waiting time is defined as the number of minutes that elapses from when the customer enters the line until he or she reaches the teller window. Data are collected from a random sample of 15 customers at each branch. Complete parts (a) through (d) below.

a. Assuming that the population variances from both banks are equal, is there evidence of a difference in the mean waiting time between the two branches? (Use =0.05.)

Find the test statistic.

tSTAT=enter your response here (Round to two decimal places as needed.)

Compare the tSTAT test statistic with the critical values.

b. Determine the p-value in (a) and interpret its meaning.

c. In addition to equal variances, what other assumption is necessary in (a)?

d. Construct and interpret a 90% confidence interval estimate of the difference between the population means between commercial and residential banks.

Commercial4.075.623.075.394.812.433.733.344.296.220.495.166.276.273.67Residentia9.745.928.135.668.513.658.068.3310.276.875.364.216.199.835.56 Commercial4.075.623.075.394.812.433.733.344.296.220.495.166.276.273.67Residentia9.745.928.135.668.513.658.068.3310.276.875.364.216.199.835.56