Crestline Bank would like to minimize its labor costs by hiring as few tellers as possible while still maintaining a stated service level. In particular, it desires the average waiting time for a...

Crestline Bank would like to minimize its labor costs by hiring as few tellers as possible while still maintaining a stated service level. In particular, it desires the average waiting time for a customer from the time he or she enters a line until the transaction is completed to be at most three minutes. Define:

 T = the number of tellers employed by Crestline Bank

 W(T) = a function giving the average customer waiting time when there are T tellers

Write a mathematical model for this problem. Is it an optimization or a prediction model?