On average, 40 cars per hour are tempted to use the drive-through window at the Hot Dog King Restaurant. (We assume that inter-arrival times are exponentially distributed.) If a total of more than four cars are in line (including the car at the window), a car will not enter the line. It takes an average of four minutes (exponentially distributed) to serve a car.

a. What is the average number of cars waiting for the drive-through window (not including the car at the window)?

b. On average, how many cars will be served per hour?

c. You have just joined the line at the drive-through window. On average, how long will it be before you receive your food?