Phone calls arrive at exchange at the rate of eight calls per minute, and the pattern of their arrival can be modeled by the Poisson distribution.
a) Find out the probability that at most 2 calls arrive in a 1-minute period.
b) Find out the probability that the waiting time for the first phone call is longer than 30 seconds.
c) Find out the probability that the waiting time for first two phone calls is longer than one minute.