4. The teller at a single drive-through window at a branch of Pecuniary BanCorp takes 3 minutes on an average to handle a customer transaction. The service time varies from customer to customer, and the standard deviation has been measured as 3 minutes. Customers arrive at the average rate of 12 per hour.

a. On an average, how many cars will be waiting in line? How long must the average customer wait before being served?

b. If the teller is provided with a computer link to the bank's database, the average time will not be shortened, but the standard deviation will drop to 45 seconds. How will this change your answers to part a?