問53
頻出度★★★
システム開発作業を実施するに当たり, 生産性が同じメンバ6名で20日間掛けて完了する計画を立てた。しかし, 15日間で作業が終わるように計画を変更することになり, 新たなメンバを増員することとした。新メンバの生産性は当初予定していたメンバの半分であるとき, 15日間で作業を終わらせるために必要な新メンバは最低何人か。
平成28年度 春期 ITパスポート試験 問53
マネジメント系プロジェクトマネジメント › プロジェクトマネジメント
This question's explanation and your answers so far.
解説
問 53
Incorrectア
One new member can only handle 0.5×15=7.5 (person-day equivalents) in 15 days, far short of the remaining 30. With just 1 member the work cannot be finished in 15 days, so this is wrong.
Incorrectイ
With 2 new members it is 7.5×2=15 (person-day equivalents), only half of the remaining 30. Still not enough to finish in 15 days, so this is wrong.
- ウ
正解 The total amount of work (effort) can be expressed as “number of people × number of days × productivity”. The original plan had 6 members with equal productivity finish in 20 days, so the total effort is 6×20=120 (person-day equivalents). To finish this in 15 days, the original 6 members still work for 15 days, handling 6×15=90 (person-day equivalents). So the remaining work is 120−90=30 (person-day equivalents). Each new member's productivity is half that of the original members, so one new member can do 0.5×15=7.5 (person-day equivalents) in 15 days. Therefore the number of new members needed is 30÷7.5=4. A minimum of 4 members exactly covers the remaining work, so the correct answer is “ウ”, 4.
Incorrectエ
With 6 new members it is 7.5×6=45 (person-day equivalents), far exceeding the remaining 30. The question asks for the minimum number of people, and since 4 members suffice, 6 is excessive, so this is wrong.
ここがポイント
- Amount of work (effort) = number of people × number of days × productivity. The total effort is fixed, so the key idea is to find the remaining work based on the original plan's effort.
- A member with half the productivity can do only half the amount even over the same number of days. Convert using the 0.5 factor first, then calculate the number of members needed.
用語