According to a 2017 survey conducted by the technology market research firm The Radicati Group, U.S. office workers receive an average of 121 e-mails per day (Entrepreneur magazine website). Assume the number of e-mails received per hour follows a Poisson distribution and that the average number of e-mails received per hour is five.
a. What is the probability of receiving no e-mails during an hour?
b. What is the probability of receiving at least three e-mails during an hour?
c. What is the expected number of e-mails received during 15 minutes?
d. What is the probability that no e-mails are received during 15 minutes?