Automobiles arrive at a drive-thru window at the rate of 4 every 10 minutes. The average service time is 2 minutes. The Poisson distribution is appropriate for the arrival rate and service times are exponentially distributed.
a) What is the average time a car is in the system?
b) What is the probability that there are exactly 2 cars in the system?
c) By how much would your answer to part (a) be reduced if a second drive-thru window, with its own server, were added?