Telephone calls arrive at a switchboard in a Poisson process at the rate of 2 per minute. A random one-tenth of the calls are long distance.
(a) What is the probability that no call arrives between 9:00-9:05am?
(b) What is the probability that at least 2 calls arrive between 10:00-10:02am?
(c) What is the probability of at least one long distance call in a ten minute period?
(d) Given that there have been 8 long distance calls in an hour, what is the expected number of calls to have arrived in the same period?
(e) Given that there were 90 calls in an hour, what is the probability that 10 were long distance?