15. Here is a network with the activity times shown in days: A(7) B(3) D(5) F(4) (G(5) (C(4) E(2) a. Find the critical path. b. The following table shows the normal times and the crash times, along with the associated costs for each activity. Activity Normal Time Crash Time Normal Cost Crash Cost A 7 6 $7,000 $8,000 B 3 2 5,000 7,000 C 3 9,000 10,2001 D 5 4 3,000 4,500 E 2 1 2,000 3,000 F 2 4,000 7,000 G 5 4 5,000 8,000