IPA FE Subject A 2024 Question 13
A question IPA Japan published in 令和６年度 基本情報技術者試験 科目A 公開問題 問13, translated into English. ITPEC is based on the same exams.
What is the minimum number of days required to complete the project represented by the arrow diagram?
Explanation
120 days — the minimum duration is the length of the longest path (the critical path), with the two dummy activities followed as 0-day dependencies.
Work out the earliest day each milestone is reached, taking the largest value where arrows meet:
The critical path is A → C → dummy → G → H: 30 + 30 + 0 + 30 + 30 = 120 days. G cannot start until C is finished, because the dummy carries C's end to G's start.
Answer (c)
Why not others:
- •(a) 105 — the length of A → B → E → H, the path through the longest activity E (40 days); a long single activity does not make the longest path
- •(b) 115 — the length of A → C → F → H, the longest path when the dummies are ignored; the dummy after C makes G wait until day 60
- •(d) 125 — no path through the diagram is that long; it overshoots the longest path by 5 days
Key rule: The minimum project duration is the longest path through the arrow diagram; at each merge take the largest earliest time, and follow every dummy as a 0-day dependency.
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.