The manager of the apartment complex in Problem 9 of Chapter 9 believes that the number of units rented during any given month has a triangular distribution with minimum 30, most likely 34, and maximum 40. Operating costs follow a normal distribution with mean $15,000 and a standard deviation of $300. Use Crystal Ball to estimate the 80%, 90%, and 95% confidence intervals for the profitability of this business.

a. What is the probability that monthly profit will be positive?

b. What is the probability that monthly profit will exceed $4,000?

c. Compare the 80%, 90%, and 95% certainty ranges.