問7
頻出度★★★
一定期間ごとに最適量を発注する方式を定期発注方式という。この定期発注方式で購買品を調達するに当たり, 発注サイクルを 10 日, 納入リードタイムを 5 日, 1 日の平均消費量を 50 個, 安全在庫量を 30 個とした場合, 今回の発注量は幾らか。ここで, 発注は, 発注日の消費終了後に行うものとし, 今回の発注時点での在庫量は 300 個で, 発注残はないものとする。
平成21年度 秋期 ITパスポート試験 問7
ストラテジ系企業活動 › 業務分析・データ利活用
This question's explanation and your answers so far.
解説
問 7
Incorrectア
420 comes from 750 - 300 - 30, subtracting the safety stock of 30 units instead of adding it. Safety stock is a reserve that must not be used up, so it should be added to the required amount; subtracting it means the stock would run out by the end of the period.
Incorrectイ
450 comes from 750 - 300, forgetting to add the safety stock of 30 units. It covers the 15 days of consumption, but the stock on hand would be exactly 0 at the time of the next delivery, leaving no safety stock.
- ウ
正解 With the fixed-interval (periodic) ordering method, the consumption from the moment of this order until “the goods of the next order are delivered” — that is, the ordering cycle of 10 days plus the delivery lead time of 5 days, or 15 days — must be covered by this order quantity, the inventory on hand, and any outstanding orders. Consumption over these 15 days is 50 units/day × 15 days = 750 units. Adding the safety stock of 30 units, which must not be used up, gives 780 units as the total that must be secured this time. Subtracting the 300 units already on hand and the 0 units on outstanding order gives 780 - 300 = 480 units. Therefore the correct answer is ウ, 480.
Incorrectエ
530 comes from 50 × 10 + 30, which neither counts the 5 days of delivery lead time nor subtracts the 300 units on hand. With the fixed-interval ordering method, the target period must include the delivery lead time, and the inventory on hand and outstanding orders must also be deducted.
ここがポイント
- Order quantity in the fixed-interval ordering method = average daily consumption × (ordering cycle + delivery lead time) + safety stock - inventory on hand - outstanding orders.
- The target period includes the delivery lead time because, even after the goods of this order arrive, the stock must last until the goods of the next order are delivered. Safety stock is added, while inventory on hand and outstanding orders are subtracted.
用語