The number of people arriving at a bicycle repair shop follows a Poisson distribution with an average of 5 arrivals per hour. Let X represent the number of people arriving per hour. a) What is the probability that seven people arrive at the bike repair shop in a one hour period of time? b) What is the probability that at most seven people arrive at the bike repair shop in a one hour period of time? c) What is the probability that more than seven people arrive at the bike repair shop in a one hour period of time? d) What is the probability that between 4 and 9 people, inclusively, arrive at the bike repair shop in a one hour period of time?