正解The correct answer is ア (Model A). The selection requirements of this question set state that an overall evaluation score is calculated from the weights and the evaluation values of the evaluation items, and that the model with the largest overall evaluation score is selected. The formula is: overall evaluation score = (weight of price × evaluation value of price) + (weight of performance × evaluation value of performance) + (weight of service × evaluation value of service). In Table 6 the weights are 2 for price, 2 for performance, and 1 for service, so calculating each model in turn gives the following. Model A = 2×7 + 2×6 + 1×5 = 14 + 12 + 5 = 31. Model B = 2×7 + 2×3 + 1×7 = 14 + 6 + 7 = 27. Model C = 2×5 + 2×3 + 1×8 = 10 + 6 + 8 = 24. Model D = 2×5 + 2×7 + 1×4 = 10 + 14 + 4 = 28. The overall evaluation scores line up as Model A (31) > Model D (28) > Model B (27) > Model C (24), so the largest is Model A. What works in Model A's favor is that it earns high evaluation values on both items that carry the larger weight of 2: price 7 and performance 6. Therefore the model selected according to the selection requirements is Model A, and the answer is ア.
×Incorrectイ
Model B's overall evaluation score is 2×7 + 2×3 + 1×7 = 27, which does not reach Model A's 31 and leaves it in third place. Its price of 7 and service of 7 are high, but its evaluation value for performance, an item with the larger weight of 2, is only 3, so it falls behind Model A by (6−3)×2 = 6 points on performance. Even though it beats Model A by 2 points on service, the weight of service is only 1, so the gap it can recover is just 2 points, and it cannot overtake Model A.
×Incorrectウ
Model C's overall evaluation score is 2×5 + 2×3 + 1×8 = 24, the lowest of the four models. Its evaluation value of 8 for service is the highest among the four models, but the weight of service is 1, the smallest, so its contribution to the overall evaluation score is only 8 points. Meanwhile the items with a weight of 2 are low: price is 5 and performance is 3. This makes it a typical example of a model that is not selected because the heavily weighted items score low, even though it is the best on one single item.
×Incorrectエ
Model D's overall evaluation score is 2×5 + 2×7 + 1×4 = 28, second only to Model A's 31. Its performance of 7 is the highest among the four models, and on performance alone it does beat Model A (6), but its price of 5 is 2 lower than Model A's 7, and since price carries a weight of 2 that is a disadvantage of 4 points; its service of 4 is also 1 lower than Model A's 5. On balance it ends up 3 points short of Model A, so it is not the one selected by the overall evaluation.
ここがポイント
Weighted overall evaluation (weighted scoring) — when comparing several options, give each evaluation item a weight that expresses its importance, compute overall evaluation score = Σ (weight × evaluation value), and choose the option with the largest total. It is a basic technique used when selecting equipment models, suppliers, or proposals, and the calculation is simply a column-wise sum of weight × evaluation value for each model.
Judge by the overall evaluation score, not by the highest value on a single item — as with Model C's service of 8 or Model D's performance of 7, being the best on one item does not decide the result when that item's weight is small. The option that scores high on the heavily weighted items (price and performance, each weighted 2, in this question) is the one that gains the advantage, and what the question tests is whether you understand how the weights work.