ITPEC FE Morning October 2020 Question 52

Reduced by 1 day — shortening D shortens its own path by 3 days, but another path then becomes critical at 15 days.

Paths from start to end (the dummy takes 0 days):

• •A → B → E: 6 + 5 + 4 = 15 days
• •C → D → E: 7 + 5 + 4 = 16 days, the critical path
• •C → dummy → F: 7 + 0 + 6 = 13 days

The project takes 16 days. With D shortened to 5 − 3 = 2 days, C → D → E becomes 7 + 2 + 4 = 13 days, and the longest path is now A → B → E at 15 days. The duration falls from 16 to 15 days.

Answer (b)

Why not others:

• •(a) — D lies on the critical path C → D → E, so shortening it does shorten the project
• •(c) — a 2-day saving would need every path to take 14 days or less, but A → B → E still takes 15
• •(d) — subtracts the full 3 days from the old critical path, 16 − 3 = 13, without checking that A → B → E, at 15 days, is now the longest

Key rule: After shortening a critical activity, recompute every path: the saving stops at the length of the next-longest path.

Project Management · AI-written, may contain errors