Customers arrive at a full-service gas station, with two pumps, at rate of 30 cars per hour. However, customers will go to another station if there are at least four cars in the station: i. e., two being served and two waiting. Suppose that the service time for customers is exponential with mean 5 minutes. Denote by Xt the number of cars at the gas station at time t (both waiting and being served). a) In the long-run, how many cars per hour are served at the station? b) If the gas station is currently empty, what is the expected time until it becomes full?