Abank manager would like to use an analytical queueing model to study the congestion at the bank’s automatic teller machines (ATMs). A simple model of this system requires that the interarrival times...

Abank manager would like to use an analytical queueing model to study the congestion at the bank’s automatic teller machines (ATMs). A simple model of this system requires that the interarrival times (times between customer arrivals to the machines) and service times (times customers spend with the machines) are exponentially distributed. During a period of time when business is fairly steady, several employees use stopwatches to gather data on interarrival times and service times. The data are listed in Figure 14.4 (with several rows hidden). The bank manager wants to know, based on these data, whether it is reasonable to assume exponentially distributed interarrival times and service times. In each case, the manager also wants to know the appropriate value of λ.

Objective To test the appropriateness of the exponential distribution for interarrival time and service time data at ATMs.