Chapter 12, Problem 41PS

A bank with a branch located in a commercial district of a city has developed an improved process for serving customer during the noon-to-1 P.M. lunch period. The bank has the business objective of reducing the waiting time (defined as the number of minutes that elapse from when the customer enters the line until he or she reaches the teller window) to increase customer satisfaction. A random sample of 15 customers is selected and waiting times are collected and stored in Bank1. These waiting times (in minutes) are:

$\begin{array}{l}4.215.553.025.134.772.343.543.20\\ 4.506.100.385.126.466.193.79\end{array}$

Another branch, located in a residential area, is also concerned with the noon-to-1 P.M. lunch period. A random sample of 15 customers is selected is selected and waiting times are collected and stored in Bank2. These waiting times (in minutes) are:

$\begin{array}{l}9.665.908.025.798.733.828.018.35\\ 10.496.685.644.086.179.915.47\end{array}$

a. Is there evidence of a difference in the median waiting time between the two branches? $(\text{Use}\alpha =\mathrm{0.05.})$

b. What assumptions must you make in (a)?

c. Compare the results (a) with those of Problem 10.12 (a) on page 360. Discuss.