AMC 8 2016 Problem 4
AMC8 2016 年第 4 题
行程问题★★☆☆☆
When Cheenu was a boy, he could run 15 miles in 3 hours and 30 minutes. As an old man, he can now walk 10 miles in 4 hours. How many minutes longer does it take for him to walk a mile now compared to when he was a boy?
当 Cheenu 还是个孩子时，他 3 小时 30 分钟内可以跑 15 英里，现在他是个老人，4 小时内可以走 10 英里。现在的他和当他还是个孩子时比起来，行过 1 英里需要多花多少分钟？
- A.6
- B.10
- C.15
- D.18
- E.30
正确答案 · Correct Answer
B
解析 · Solution
Solution 1
When Cheenu was a boy, he could run 15 miles in 3 hours and 30 minutes = 3×60 + 30 minutes = 210 minutes, thus running minutes per mile. Now that he is an old man, he can walk 10 miles in 4 hours = 4×60 minutes = 240 minutes, thus walking minutes per mile. Therefore, it takes him 10 minutes longer to walk a mile now compared to when he was a boy.
From the question, the old man can travel five miles in two hours, so we can set both speeds to 15 miles. We can see that Cheenu as an old man takes 2 hours and 30 minutes for him to travel 15 miles, which is also 150 minutes. We can then divide this by fifteen, which gives us 10, thus the answer is
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