Customers arrive at a service station with the intensity A = 5 per hour. Assume that customer arrivals form a Poisson process, X = (X(t): 20). Introduce for any natural k, such that k 21, the arrival times, W = min [t 01X(t) = k]. 1. Given that the eighth customer arrived exactly at the end of third hour, or Wa= 3, find the conditional density of the forth arrival time (W). 2. Evaluate E (W Ws=3] and Var [WW=3]