4. A small branch bank has a single drive-in window. The customer arrival rate is Poisson-distributed with a mean of 14 customers per hour. Service times are exponentially distributed with a mean of 3 minutes per customer.

a. Compute the utilization of the window and the teller who services it.

b. How long does the average customer who uses the window spend waiting and being served?

c. What is the average number of vehicles in the line (including the one being served)?