丹尼斯在一项调查中回答了 20 个问题。前 10 个问题她每个用时 3 分钟，其余的问题每个用时是前者的两倍。她于下午 1:20 开始该调查。她是在什么时间完成调查的？

它不会直接告诉你答案，而是问你卡在哪一步看看 AI 是怎么陪你一步步弄懂这道题的

完整解法

1. Calculate the time taken for the first 10 questions

Time for first 10 questions = $10 \times 3 = 30$ min

2. Calculate the time taken for the remaining 10 questions

Time per remaining question = $3 \times 2 = 6$ min
Time for remaining 10 questions = $10 \times 6 = 60$ min

3. Calculate the total time taken

Total time = $30 + 60 = 90$ min = 1 h 30 min

4. Determine the completion time

Start time = 1.20 p.m.
Completion time = 1.20 p.m. + 1 h 30 min = 2.50 p.m.

答案

2.50 p.m.

AI 分析，可能出错

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