Representatives from the American Heart Association are planning to go door-to-door throughout a community, soliciting contributions. From past experience, they know that when someone answers the door, 80% of the time it is a female and 20% of the time it is a male. They also know that 70% of the females who answer the door make a donation, whereas only 40% of the males who answer the door make donations. The amount of money that females contribute follows a normal distribution with a mean of $20 and standard deviation of $3. The amount of money that males contribute follows a normal distribution with a mean of $10 and standard deviation of $2.

a. Create a spreadsheet model that simulates what might happen whenever a representative of the American Heart Association knocks on a door and someone answers.
b. Replicate your model 5000 times. What is the average contribution the Heart Association can expect to receive when someone answers the door?
c. Suppose that the Heart Association plans to visit 300 homes on a given Saturday. If no one is home at 25% of the residences, what is the total amount that the Heart Association can expect to receive in donations?