CHAPTER 9
QUEUEING MODELS
Internet Case Study: Pantry Shopper
Beth wants to get a general idea of the system behavior. She first will need to decide whether she is
interested in time waiting or time in system. Some students may use system time, but since most shoppers
are relieved when it is their turn, we use waiting time as our measure. For all of our analyses, we use
See file Ch09 Internet Case Pantry Shopper.XLS, see sheet #1. With an arrival rate of 100 per hour and a
service rate of 16.67 per hour, the minimum number of servers required is 7, and the average waiting time
is 2.2 minutes. Adding one more server leads to a waiting time of 0.64 minutes.
Now we separate the express and regular customers. Assume that all express customers go into the
express (even though they can go into any lane) and assume that all non-express customers go into the
proper lanes (even though we all have seen people with twenty packages get into an express line).