A business school is considering replacing its old minicomputer with a faster model. Past records show that the average student arrival rate is 24 per hour, Poisson dis­ tributes, and that the service times are distributed exponentially.

The computer se­ lection committee has been instructed to consider only machines that will yield an average turnaround time (i.e., expected time in the system) of 5 minutes or less. What is the smallest computer-processing rate per hour that can be considered?