Events occur according to a Poisson process with rate = 4 per hour.
(a) What is the probability that 2 or more events occur in the first 30 minutes?
(b) What is the probability that exactly 5 events occur in the first 90 minutes?
(c) What is the expected value of the number of events that occur in the first 6 hours?
(d) What is the expected length of time required for 8 events to occur?