68. Mall Rats An article in American Demographics claims that more than twice as many shoppers are out shopping on the weekends than during the week.7 Not only that, such shoppers also spend more money on their purchases on Saturdays and Sundays! Suppose that the amount of money spent at shopping centers between 4 p.m. and 6 p.m. on Sundays has a normal distribution with a mean of $185 and a standard deviation of $20.

A shopper is randomly selected on a Sunday between 4 p.m. and 6 p.m. and asked about his spending patterns.

a. What is the probability that he has spent more than

$195 at the mall?

b. What is the probability that he has spent between

$195 and $215 at the mall?

c. If two shoppers are randomly selected, what is the probability that both shoppers have spent more than

$215 at the mall?