A company must perform a maintenance project consisting of seven activities. The activities, their predecessors, and their respective time estimates are presented here:
Immediate
Activity Designation Predecessor Time in Days
Break down both machines A None 3
Clean machine 1 B A 3
Clean machine 2 C A 3
Re-set machine 1 D B 4
Re-set machine 2 E C 2
Re-calibrate both machines F D and E 1
Final test G F 1
Using CPM, which activities have slack in this project?
a. A, B, C
b. B, D
c. Only C
d. C, E
e. F, G