AMC8 2016

AMC8 2016 · Q4

AMC8 2016 · Q4. It mainly tests Rates (speed).

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?

Cheenu小时候能在3小时30分钟内跑15英里。现在作为老人，他能在4小时内走10英里。现在走一英里比小时候多花多少分钟？

(A) 6 6

(B) 10 10

(D) 18 18

(E) 30 30

Answer

Correct choice: (B)

正确答案：（B）

Solution

As a boy it took Cheenu 3 hours and 30 minutes, which is 210 minutes, to go 15 miles. That is a rate of $210 \div 15 = 14$ minutes per mile. As an old man it takes him 4 hours, or 240 minutes, to travel 10 miles. That is a rate of $240 \div 10 = 24$ minutes per mile. It takes him $24 - 14 = 10$ minutes more to walk a mile as an old man.

作为男孩，Cheenu 走15英里用了3小时30分钟，即210分钟。速度是每英里 $210 \div 15 = 14$ 分钟。作为老年人，他走10英里用了4小时，即240分钟。速度是每英里 $240 \div 10 = 24$ 分钟。作为老年人，走一英里比从前多用 $24 - 14 = 10$ 分钟。

Topics

AR.007 Rates (speed)