An airport shuttle bus picks up passengers waiting at a bus stop and drops them off at the airport terminal; it then returns to the stop and repeats the process. The times between returns to the stop are independent random variables with distribution F, mean μ, and variance σ2. Passengers arrive at the bus stop in accordance with a Poisson process with rate λ. Suppose the bus has just left the stop, and let X denote the number of passengers it picks up when it returns. a) Find E[X]. b) Find Var(X). c) At what rate does the shuttle bus arrive at the terminal without any passengers? d) Suppose that each passenger that has to wait at the bus stop more than c time units writes an angry letter to the shuttle bus manager. e). What proportion of passengers write angry letters? e) How does your answer in part (d) relate to