正解The fee is determined by finding the category from the sum of the 3 sides and the category from the weight separately, taking whichever category is larger, and then reading the amount from Table 1. In row 1, C / sum of 3 sides 60 cm / weight 5 kg: 60 cm falls in category 1 (up to 80) and 5 kg also falls in category 1 (up to 5), so category 1 applies and the correct fee is 1,150 yen for district C. However, the output is 1,400 yen, which is the value for category 2, district C in Table 1, so it is wrong. Row 3, D / 60 cm / 5 kg, is likewise category 1 and should be 1,800 yen, but the output is 2,350 yen (category 2, district D), which is also wrong. On the other hand, in row 2, C / 101 cm / 8 kg, 101 cm falls in category 3 (up to 140) and 8 kg in category 2, so the larger category 3 applies and the fee is 1,800 yen; row 4, D / 101 cm / 8 kg, is also category 3 at 3,400 yen, and both of these match the output and are correct. In other words, errors appear only for the input with a sum of 3 sides of 60 cm and a weight of 5 kg, so ア is appropriate.
×Incorrectイ
Category 3 applies to the two rows with a sum of 3 sides of 101 cm (C at 1,800 yen and D at 3,400 yen), and both match the category 3 values in Table 1 exactly, so they are correct. The rows that are actually wrong are instead the 60 cm / 5 kg rows, where category 1 should apply, so judging that the output is wrong when category 3 applies is the opposite of the truth.
×Incorrectウ
The correct fee for C / 60 cm / 5 kg is 1,150 yen and for D / 60 cm / 5 kg is 1,800 yen, which do not agree with the actual outputs of 1,400 yen and 2,350 yen. In 2 of the 4 rows the expected value differs from the output, so it cannot be said that there are no errors in the output results.
×Incorrectエ
The errors appear not only in district C but in district D as well. The output 2,350 yen for D / 60 cm / 5 kg is likewise the value of category 2, one step above the correct 1,800 yen (category 1, district D), so it is also wrong. What separates the wrong results from the correct ones is not the district but the input side: a sum of 3 sides of 60 cm and a weight of 5 kg.
ここがポイント
The size category is judged separately for the sum of the 3 sides and for the weight, and the larger of the two is applied. Since “up to 80” and “up to 5” include the boundary values, 60 cm and 5 kg fall in category 1, not category 2.
Judging whether a test passes means preparing the expected output first, comparing it with the actual output, and reading off the common pattern in the errors. Here the error “what should be category 1 is charged at category 2” appears regardless of the district, so the cause can be pinpointed on the side of the input conditions.