A ISEN student gets a job managing a movie theater. After a couple of days on the job, he notices that prior to 6:00pm people arrive to buy tickets according to a Poisson process with an average rate of 10 customers per hour. Only one cashier is at the window during these non-peak hours. The time it takes the cashier to complete a ticket sales transaction is exponentially distributed with = 30/hour. If a customer arrives and finds the cashier busy, they join a queue that operates in a first-come, first- served manner. (a) What is the probability that an arriving customer has to wait in line? (b) How many customers on average are either at the window or in line? (c) What is the average waiting time of a customer