A real estate agent has four houses to sell before the end of the month by contacting prospective customers one by one. Each customer has an independent 0.24 probability of buying a house on being contacted by the agent.

a. If the agent has enough time to contact only 15 customers, how confident can she be of selling all four houses within the available time?

b. If the agent wants to be at least 70% confident of selling all the houses within the available time, at least how many customers should she contact? (If necessary, extend the template downward to more rows.)

c. What minimum value of p will yield 70% confidence of selling all four houses by contacting at most 15 customers?

d. To answer (c) above more thoroughly, tabulate the confidence for p values ranging from 0.2 to 0.6 in steps of 0.05.