On a CPM/PERT network if activity 3 with an activity time of 1,ES=3 and LS=4,is followed by activity 4 with an activity time of 3 and LF=8,and activity 5 with an activity time of 1 and LF=7,the LS for activity 3 is
A)3
B)4
C)5
D)6

Question

Quizplus · Accepted Answer

LS (latest start) for an activity is the latest time it can start without delaying the project. In this case, Activity 3 has ES (earliest start) of 3 and Activity 4 has LF (latest finish) of 8. The duration of Activity 3 is 1, so we can calculate the LF of Activity 3 as 8-1=7. Therefore, the LS of Activity 3 is LF of its successor (Activity 4) minus its duration, which is 8-1=7. Since the LS of Activity 3 is 4, which is earlier than 5 or 6, the correct answer is B.

On a CPM/PERT Network If Activity 3 with an Activity