Almost all computer hardware and software producers offer a toll-free telephone number to solve problems associated with their products. The ability to work quickly to resolve difficulties is critical. One software maker’s policy is that all calls must be answered by a software consultant within  120 seconds. (All calls are initially answered by computer and the caller is put on hold until a consultant attends to the caller.) To help maintain the quality of the service, four calls per day are monitored. The amount of time before the consultant responds to the calls was recorded for the last 30 days.

a. Draw the appropriate control chart(s).
b. Does it appear that the process went out of control? If so, when did this happen, and what are the likely causes and remedies?