A small nonprofit organization is planning a door-to-door marketing campaign to sell Christmas wrapping and gifts. They plan to visit 100 homes. Consultants have estimated that they should expect to find someone home 80 percent of the time. When someone is home, 65 percent of the time it is a female. Thirty percent of females make a purchase, and when they do so the dollar value of their purchase is normally distributed with a mean of $22 and a standard deviation of $5. Males purchase 20 percent of the time, and the dollar value of their purchase is normally distributed with a mean of $28 and a standard deviation of $3.

a. What is the total amount they can expect to generate in revenues from these 100 visits?
b. What is the standard deviation of total revenues over 100 visits?
c. What is the probability they will make more than $750?