In January 2003, the American worker spent an average of 77 hours per month logged on the Internet (CNBC,
March 15, 2003). Assume that the population mean is 77 hours, the times are normally distributed, and that the standard deviation is 20 hours.

a) What is the probability that in January of 2003 a randomly selected worker spent fewer than 50 hours per month logged on to the Internet?

b) A person is qualified as heavy user if he or she is in the upper 20 % of usage. In January of 2003, how many hours did a worker have to be logged on to the Internet to be considered a heavy user?