This question's explanation and your answers so far.
あるコールセンターでは,顧客からの電話による問合せに対応するオペレーターを支援するシステムに,顧客とオペレーターの会話の音声を認識し,顧客の問合せに対する回答の候補をオペレーターの PC の画面に表示する AI を導入した。1日の対応件数は1,000件であり,問合せ内容によって二つのグループ A,B に分けた。AI 導入前後の各グループの対応件数,対応時間が表のとおりであるとき,AI 導入後に,1,000件の問合せに対応する時間は何%短縮できたか。 AI 導入前後のグループ別の対応件数と対応時間
| グループA 対応件数 | グループA 対応時間 | グループB 対応件数 | グループB 対応時間 | |
|---|---|---|---|---|
| AI 導入前 | 800件 | 全体の60% | 200件 | 全体の40% |
| AI 導入後 | 800件 | AI 導入前と比べて50%短縮 | 200件 | AI 導入前と同じ時間 |
正解 Let the total handling time for all inquiries before introducing the AI be 100%; from the table, Group A accounts for 60% of it and Group B for 40%. After introducing the AI, Group A is “50% shorter than before AI,” so it becomes 60%×(1−0.5)=30%, while Group B keeps the “same time as before AI,” remaining 40%. The total handling time after introduction = 30%+40% = 70%. Therefore the reduction is 100%−70% = 30%. Matching this to the options (30/40/50/60) gives 30, so the correct answer is ア. The key point is that the reduction occurs only in Group A, and its size is “half of the overall 60% = 30% of the total.”
40 mistakes the share of Group B (40% of the total) for the amount reduced. What was shortened is Group A, which was cut by 50%, while Group B is unchanged, so 40 is not the amount of reduction.
50 mistakes Group A’s reduction rate of “50%” directly for the overall amount reduced. The 50% reduction applies only to Group A (60% of the total), so its contribution to the whole is 60%×50% = 30%, not 50.
60 mistakes Group A's pre-reduction share (60% of the total) for the amount reduced. Group A is only shortened by 50% (i.e., the 30% portion) and does not drop to 0%, so 60 is too large and incorrect.