According to a 2017 survey conducted by the technology market research firm The Radicati Group, U.S. office workers receive an average of 121 emails per day (Entrepreneurmagazine website). Assume the number of emails received per hour follows a Poisson distribution and that the average number of emails received per hour is five.

1. What is the probability of receiving no emails during an hour?
2. What is the probability of receiving at least three emails during an hour?
3. What is the expected number of emails received during 15 minutes?
4. What is the probability that no emails are received during 15 minutes