問15
頻出度★★☆
1個の製品Pは2個の部品Qで構成され, 部品Qは4個の部品Rで構成されている。部品Qは1個, 部品Rは3個の在庫があるとき, 製品Pを6個生産するには, 部品Rはあと何個必要か。
平成30年度 春期 ITパスポート試験 問15
This question's explanation and your answers so far.
解説
問 15
- ア
正解 In parts explosion, the requirements for lower-level parts are worked out level by level. To make 6 units of product P you need 6×2=12 parts Q, but since 1 part Q is in stock, the number of Q to newly make is 12−1=11. To make these 11 parts Q you need 11×4=44 parts R, and since 3 parts R are in stock, the number of R still needed is 44−3=41. Therefore the correct answer is ア “41”.
Incorrectイ
44 stops at the gross requirement for R, 11×4=44, computed from the net required Q (11 units), and forgets to subtract the 3 parts R in stock. You must subtract the R stock at the end to get 41.
Incorrectウ
45 comes from not subtracting the 1 part Q in stock: keeping the Q requirement at 12 gives 12×4=48 parts R, and then subtracting only the 3 parts R in stock gives 48−3=45. The Q stock was not subtracted first.
Incorrectエ
48 is the gross requirement 6×2×4=48 that ignores stock entirely. Since neither the Q stock nor the R stock is subtracted, it is not the additional quantity needed.
ここがポイント
- Parts explosion in MRP (Material Requirements Planning): gross requirement = required quantity × number of component parts, calculated in order from higher to lower levels.
- Net requirement = gross requirement − stock. The key point is to subtract stock at each level (for both Q and R) before calculating the requirement for the lower-level parts.
用語