Airline passengers arrive randomly and independently at the passenger-screening facility at a major international airport. The mean arrival rate is 9 passengers per minute.

1. Compute the probability of no arrivals in a one-minute period (to 6 decimals).

1. Compute the probability that three or fewer passengers arrive in a one-minute period (to 4 decimals).

1. Compute the probability of no arrivals in a 15-second period (to 4 decimals).

1. Compute the probability of at least one arrival in a 15-second period (to 4 decimals).