MonoMachine Co. specializes in developing harvesting equipment. CEO of the company is contemplating the construction of a machine that would harvest on narrow rivers and waterways. The activities that are necessary to build one of these experimental harvesting machines are listed in the following table. Immediate Time (weeks) Activity Predecessor Optimistic Probable Pessimistic A - 4 7 10 B - 2 6 7 C A 1 3 5 D A 1 2 3 E B 3 5 7 F B 4 6 11 G C, E 6 12 15 H D, F 5 9 13 a) Draw a project network, and determine the slack for each activity. b) Find the expected project completion time and critical path.