1. Building a backyard swimming pool consists of nine major activities. The activities and their immediate predecessors are shown. Activity A Immediate predecessor C E F GH I - A,B A,B B C D D,F E,G,F Assume that the activity time estimates (in days) for the swimming pool construction are as follows: Activity Optimistic Most Probable Pessimistic A 3 5 6 B 2 4 6 C 5 6 7 D 7 9 10 E 2 4 6 F 1 2 3 G 5 8 10 H 6 8 10 I 3 4