Sharp discounts wholesale club has two service desks, one at each entrance of the store. Customers arrive at each service desk at an average of one every six minutes. The service rate at each service desk is four minutes per customer.

A. How often ( what percentage of time ) is each service desk idle ?

B. What is the probability that both service clerks are busy ?

C. What is the probability that both service clerks are idle ?

D. How many customers, on average, are waiting in line in front of each service desk ?

E. How much time does a customer spend at the service desk ( waiting plus service time )?