IPA IP 2020 Question 55

Topic: Project Management

A question IPA Japan published in 令和2年度 10月 ITパスポート試験 公開問題 問55, translated into English. ITPEC is based on the same exams.

What are the shortest required days and the longest required days of the process in the figure?

A30 – 35B50 – 60C70 – 100
LegendActivity nameRequired days(Shortest – Longest)
OptionShortest required daysLongest required days

Explanation

Shortest 80 days, longest 100 days — the process ends only when both paths, A then B and C, have finished, so take the longer path in each case.

The end node is reached after both A → B and C are complete:

CaseA + BCRequired days
Shortest30 + 50 = 807080
Longest35 + 60 = 95100100

In the shortest case A → B is the critical path (80 > 70); in the longest case C is (100 > 95).

Answer (d)

Why not others:

  • •(a) 70, 95 — takes the shorter path in each case instead of the longer one
  • •(b) 70, 100 — uses C alone for the shortest case, but A → B still needs 80 days
  • •(c) 80, 95 — uses A → B alone for the longest case, ignoring that C can take 100 days

Key rule: Parallel paths finish together only when the longest one does: the project's duration is the maximum over its paths, worked out separately for each set of activity durations.

Project Management · AI-written, may contain errors

Practice this exam

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.