17 An electrical contractor is examining the amount of time his crews take to complete wiring jobs. Some crews seem to take longer than others. For an upcoming job, a list of activities and their optimistic, most likely, and pessimistic completion times are given in the following table.

ACTIVITY DAYS IMMEDIATE a m b PREDECESSORS A 3 6 9 —

B 2 4 6 —

C 1 2 3 —

D 6 7 8 C E 2 4 6 B, D F 6 10 14 A, E G 1 2 6 A, E H 3 6 9 F I 10 11 12 G J 14 16 21 G K 2 8 11 H, I

(a) Develop a project network for this problem.

(b) Determine the expected duration and variance for each activity.

(c) Determine the EST, EFT, LST, LFT, and slack for each activity. Also determine the total project completion time and critical path(s) for installing electrical wiring and equipment.

(d) What is the probability that this job will finish in 38 days or less?