6. A fast-food restaurant has one drive-through window. An average of 10 customers per hour arrive at the window. It takes an average of 4 minute to serve a customer. Assume that interarrival and service times are exponential and the waiting space is unlimited. (a) (5) What does "M/M/1" mean? (b) (3) What is the definition of a Birth-Death process? (c) (3) Give the state diagram for this queueing system (d) (2) Give a flow balance equation between state j and state (j-1). (e) (3) On the average, how many cars are waiting before service (not including the car being served at the window)? (1) (3) On the average, how long does a customer spend at the restaurant (from time of arrival to time service is completed)? (g) (3) What fraction of the time are more than 2 cars in the drive-through line (including the car being served at the window and the cars waiting)? (h) (3) If the arrival demand is increased by 20%, how will the answer in part (t), i.e., the total restaurant time, be changed