A project has the following activities with the durations in days: • Activity A : Duration = 5 days • Activity B : Duration = 3 days (starts after A) • Activity C : Duration = 4 days (starts after A) • Activity D : Duration = 2 days (starts after B and C) What is the total duration of the project in the Critical Path Method (CPM)?
- A10 days
- B12 days
- C11 daysCorrect
- D13 days
Solution
Concept
Critical path duration
Formula
Duration = longest path
Step-by-step solution
1. Paths: A–B–D = 5 + 3 + 2 = 10 days; A–C–D = 5 + 4 + 2 = 11 days. 2. Project duration = longest path = 11 days.
Explanation
B and C both start after A, and D follows both, so the longer branch (C, 4 days) governs.
Why the other options are wrong
10 days is the path through B; 12 and 13 days are not obtained from any path.
Shortcut
Take the longest branch.
Common mistake
Adding all four durations (14).
Correct answer: C) 11 days