More than 50 million guests stayed at bed and breakfasts (B&Bs)  last year. The Web site  for the Bed and Breakfast Inns of North America  , which averages  approximately seven visitors per minute, enables many  B&Bs to attract guests without waiting years to be mentioned in  guidebooks (Time, September 2001).
a. Compute the probability of no Web site visitors in a one-minute period.
b. Compute the probability of two or more Web site visitors in a one-minute period.
c. Compute the probability of one or more Web site visitors in a 30-second period.
d. Compute the probability of five or more Web site visitors in a one-minute period.