A drive-through process a Sandwich shop has three activities. The first activity is ordering; on average this process takes 2 minutes. Then, a car proceeds to the payment window; on average this process takes 2 minutes. The last activity is picking-up the order, which on average this process takes 3 minutes. There is a waiting before each of these activities. On average, there are usually 2 cars waiting to place their orders; 2 cars waiting to pay the total; and 2 cars waiting to pick-up order. On average 10 cars an hour enters the line, and assume no cars leave this process until they pick-up their order.

a Clearly draw the process flow diagram for cars. Make sure you label each activity and buffer with appropriate Littles Law variables. (6)

b On average, how long does the entire process flow take and how many cars are in the system? (4)