A bank with a branch situated in a commercial district of the city has the business objective of enhancing the procedure for serving customers throughout the noon-to-1 P.M. lunch period. To do so, the waiting time (stated as the time elapsed from when the customer enters the line till he or she reaches the teller window) requires to be shortened to raise customer sat- is faction. A random sample of 15 customers is chosen (and stored in bank 1), and the results (in minutes) are as follows:
4.21 5.55 3.02 5.13 4.77 2.34 3.54 3.20 4.50 6.10 0.38 5.12 6.46 6.19 3.79
Assume that another branch, situated in a residential area, is as well concerned with the noon-to-1 P.M. lunch period. A random sample of 15 customers is chosen (and stored in bank 2), and the results (in minutes) are as follows:
9.66 5.90 8.02 5.79 8.73 3.82 8.01 8.35 10.49 6.68 5.64 4.08 6.17 9.91 5.47
a. Is there evidence of the difference in the unpredictability of the waiting time between the two branches? (Use a = 0.05.)
c. What supposition regarding the population distribution of two banks is necessary in (a)? Is the assumption valid for these data?
d. Based upon the results of (a), is it suitable to employ the pooled-variance t test to compare the means of two branches?