Suppose small aircraft arrive at a certain airport according to a Poisson process with per hour, so that the number of arrivals during a time period of t hours is a Poisson random variable with parameter .
a) What is the probability that exactly 6 small aircraft arrive during a 1-hour period? At least 6?
b) What are the expected value and standard deviation of the number of small aircraft that arrive during a 90-min period?