Problem 4 A fast-food restaurant has one drive-through window. An average of 40 customers per hour arrive at the window. It takes an average of 1 minute to serve a customer. Assume that arrival and service times are Poisson and exponential, respectively. 1) On the average, how many customers are waiting in line? 2) On the average, how long does a customer spend at the restaurant (from time of arrival to time service is completed)? 3) What is the probability of existing more than 3 cars in the system? 3