A fast food restaurant has one drive through window. An average of 40 customer per-hour arrive at window. It takes average of one minute to serve a customer. Suppose that inter-arrival as well as service times are exponential.
a. On the average, how many customers are waiting in line?
b. On the average, how long does a customer spend at restaurant (from time of arrival to time service is completed)?
c. What fraction of time are more than three cars waiting for service (this includes the car (if any) at the window)?