A Bank Is Designing a New Branch Office and Needs

Multiple Choice

A bank is designing a new branch office and needs to determine how much driveway space to allow for cars waiting for drive-up teller service. The drive-up service will have three tellers and a single waiting line. At another branch of the bank in a similar setting, the average service time for drive-up tellers is four minutes per customer, and average arrival rate is 36 customers per hour. It is expected that the new bank will have similar characteristics.
How many spaces should be provided to have a 96 percent probability of accommodating all of the waiting cars?

A) 10
B) 11
C) 12
D) 13
E) 14