Buses arrive at a certain stop according to a Poisson process with rate lambda. If you take the bus from that stop then it takes a time R, measured from the time at which you enter the bus, to arrive home. If you walk from the bus stop, it takes a time W to arrive home. Suppose that your policy when arriving at the bus stop is to wait up to a time s, and if a bus has not yet arrived by that time then you walk home. Compute the expected time from when you arrive at the bus stop until you reach home