4. Duncan Tank is a plumber who has been given a small project that is represented by the following AON precedence network. Duncan is uncertain about the duration of each task; however, he has estimated several possible durations and their respective probabilities that follow the precedence network.

TaskA Task C Task B

a. If Duncan uses the classic PERT model and wants to give his customer a due date that has at least a 60 percent chance of occumng, what is the earliest date he Duncan can promise that the project will be completed?

b. In reality, what is the earliest date that Duncan should promise the project will be completed with at least a 60 percent probability that this will occur?