Activity R on a CPM network has predecessors M and N, and has successor S. R has duration 5. N's late finish is 18, while M's is 20. S's late start is 14. Which of the following is definitely true?
A) R is critical and has zero slack.
B) R has no slack but is not critical.
C) The set of given times cannot all be possible.
D) N is a critical activity.
E) S is a critical activity.

Question

Quizplus · Accepted Answer

Given the late start of S is 14 and R has a duration of 5, R's late finish should be at least 19 to start S on time. However, N's late finish is 18, which contradicts the possibility of starting R after N finishes if we are to meet S's late start. This inconsistency indicates that the set of given times cannot all be possible.

Activity R on a CPM Network Has Predecessors M and N