IPA IP 2022 Question 43
A question IPA Japan published in 令和4年度 ITパスポート試験 公開問題 問43, translated into English. ITPEC is based on the same exams.
In the arrow diagram in the figure, activity B was completed 2 days late. Therefore, in order to complete all the activities within the scheduled period, it was decided to add personnel to activity D. When 20 personnel are initially assigned to activity D, what is the minimum number of personnel that need to be added to activity D? Here, the work efficiency of the personnel is uniform.
Explanation
5 personnel — find how many days D may now take without delaying the end, then turn D's fixed amount of work into the staff it needs.
Planned schedule: A + C = 5 + 5 = 10 days and B = 10 days both reach the middle node on day 10. From there D takes 10 days and E + F = 4 + 4 = 8 days, so everything ends on day 20.
B finishing 2 days late moves the middle node to day 12. To end on day 20, D must finish in 20 − 12 = 8 days (E + F still fits: 12 + 8 = 20).
D's work is 20 × 10 = 200 person-days. Done in 8 days it needs 200 ÷ 8 = 25 personnel, so 25 − 20 = 5 must be added.
Answer (d)
Why not others:
- •(a) 2 — 22 personnel need 200 ÷ 22 ≈ 9.1 days, more than the 8 available
- •(b) 3 — 23 personnel need 200 ÷ 23 ≈ 8.7 days, more than the 8 available
- •(c) 4 — 24 personnel need 200 ÷ 24 ≈ 8.3 days, still over 8
Key rule: With uniform efficiency, work in person-days is fixed: required staff = person-days ÷ days available, rounded up, minus the staff already assigned.
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.