4.102 When buying property, one of the main considerations for a homebuyer is the reputation of a property developer, that is, if they follow good construction practices, offer financial security, and deliver on time. For the previous month, a random sample of the daily number of units sold at a new housing area by one of the top property developers in your state is recorded as follows: 8, 6, 7, 10, 6, 14, 6, 6, 6, 11, 12, 7, 9, 15, 8, 11, 12, 9, 8, 9.

a. What probability model should be used and why?

b. What is the probability that 10 or more units will be sold on a typical future date?

c. What is the probability of selling less than 7 units?

d. Find the number of units sold such that the probability of exceeding this number is 10% or less.