11-18 The Laurenster Corporation is getting into the con- struction business. A list of activities and their optimistic, most likely, and pessimistic completion times are given in the following table for the next construction project. DAY'S b m ACTIVITY a IMMEDIATE PREDECESSORS ABC 3 6 9 2 4 6 1 2 3 D 6 7 8 C E 2 4 6 B, D F 6 10 G 1 2 H 6 I 10 11 14 16 K 2 8 11 16922= 14 A, E A, E F G G H, I (a) Develop a project network for this problem. (b) Determine the expected duration and variance for each activity. (c) Determine the ES, EF, LS, LF, and slack time for each activity. Also determine the total proj- ect completion time and critical path(s). (d) What is the probability that this job will finish in 38 days or less? 2:11-22 A project was planned using PERT with three time estimates. The expected completion time of the project was determined to be 40 weeks. The vari- ance of the critical path is 9. (a) What is the probability that the project will be finished in 40 weeks or less? (b) What is the probability that the project will take longer than 40 weeks? (c) What is the probability that the project will be finished in 46 weeks or less? (d) What is the probability that the project will take longer than 46 weeks? (e) The project manager wishes to set the due date for the completion of the project so that there is a 90% chance of finishing on schedule. Thus, there would only be a 10% chance the proj- ect would take longer than this due date. What should this due date be?