Suppose small aircraft arrive at a certain airport according to a Poisson process with rate per hour, so that the number of arrivals during a time period of t hours is a Poisson rv with parameter .

a. What is the probability that exactly 6 small aircraft arrive during a 1-hour period? At least 6? At least 10?

b. What are the expected value and standard deviation of the number of small aircraft that arrive during a 90-min period?

c. What is the probability that at least 20 small aircraft arrive during a 2.5-hour period? That at most 10 arrive during this period?