正解Column I (cumulative sales composition ratio) is calculated after cells A2 to H11 have been sorted in descending order by column B (sales), so the composition ratios are added up in order from the largest sales. Product え 28.8% → Product う 51.3% (28.8+22.5) → Product あ 66.1% (+14.8) → Product こ 76.9% (+10.8), so the items whose cumulative ratio stays within 70% are the three items Product え, Product う, and Product あ. Next, looking at the inventory turnover ratios of these three: Product え = 9.2 times, Product う = 12.0 times, Product あ = 14.4 times, and only Product え meets the condition of 10 times or less. Therefore there is 1 priority product, and the correct answer is ア. The key point is to narrow down using the two conditions, cumulative ratio within 70% and turnover ratio of 10 times or less, joined by AND (both must hold).
×Incorrectイ
Two items result when the extraction condition is misread as a turnover of 10 times or **more**. The three items within the 70% cumulative ratio are Product え (9.2), Product う (12.0) and Product あ (14.4), and two of them, Product う and Product あ, have a turnover of 10 or more. The condition in the question is 10 times or less, so only Product え qualifies, giving one item.
×Incorrectウ
Three items is the count of Product え, Product う, and Product あ, obtained by filtering with only the condition of a cumulative ratio within 70%. It is the mistake of forgetting to also apply the second condition of a turnover ratio of 10 times or less; Product う (12.0 times) and Product あ (14.4 times) are excluded.
×Incorrectエ
Four items is the count obtained by simply taking the top four after sorting in descending order (Product え, Product う, Product あ, and Product こ). Including Product こ makes the cumulative ratio 76.9%, which exceeds 70%, and its turnover ratio of 14.0 times does not satisfy the 10-times-or-less condition either, so this is wrong.
ここがポイント
The cumulative sales composition ratio follows the idea of ABC analysis (Pareto chart): first sort by sales in descending order, then add up the composition ratios from the top downward. If the sort order is wrong, every cumulative value shifts as well.
When there are multiple extraction conditions, apply them together as AND conditions. Here, the cumulative ratio within 70% narrows it to three items, and the inventory turnover ratio of 10 times or less narrows it further to one item. Inventory turnover ratio = sales ÷ average inventory.