IPA FE Subject A 2025 Question 14
A question IPA Japan published in 令和７年度 基本情報技術者試験 科目A 公開問題 問14, translated into English. ITPEC is based on the same exams.
The figure shows activities A through I of a project and the number of days required for each activity. What is the minimum number of days required for this project?
Explanation
31 days — the minimum duration is the length of the longest path from start to end (the critical path), with the dummy activities followed as dependencies.
Work out the earliest day each milestone is reached, taking the largest value where arrows meet:
The critical path is A → B → G → dummy → D → I: 3 + 6 + 11 + 6 + 5 = 31 days.
Answer (d)
Why not others:
- •(a) 27 — the length of A → E → dummy → C → D → I, a shorter path; the project takes as long as its longest path
- •(b) 28 — the length of A → F → D → I (or A → B → C → D → I); it misses that D cannot start before G and its dummy end on day 20
- •(c) 29 — what ignoring the dummy after G gives: D could then start on day 17, and the longest path would be A → B → H → I
Key rule: The minimum project duration is the longest path through the arrow diagram; at each merge take the largest earliest time, and treat a dummy as a 0-day dependency that must still be followed.
Project Management · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.