A construction activity has an uncertain duration (D) for competition. The duration was subjectively evaluated based on prior experiences with similar activities using a pessimistic estimate, best estimate, and optimistic estimate of 90, 120, 150 days. Determine the following probabilities:

(a) P(D >

100),

(b) P(D < 140),

(c) P(D = 125), and

(d) P(100 < D < 130).