Question: An airplane takes exactly 6 minutes to land after it receives the clear-to-land signal from the airport's traffic control. Suppose that airplanes arrive according to a Poisson process, with rate λ = 6 arrivals per hour, and that only one airplane can land at a time.
a) How long can an airplane expect to circle before getting the clear-to-land signal?
b) How many airplanes are expected to wait for such a signal in stationary conditions?