Question 5I need help how to resolve this question

5. "Customers arrive at a checkout counter in a department store according to a Poisson distribution at an average of seven per hour. a) During a given hour, what is the probability that no more than three customers arrive? b) During a given hour, what is the probability that at least two customers arrive? C ) During a given hour, what is the probability that exactly five customers arrive? d) What is the probability that exactly two customers arrive in a two-hour period of time between 2pm and 4pm