Prep 1道数学题 help!就要考试了

A hiker walking at a constant rate of 4 miles per hour is passed by a cyclist travelling in the same direction along the same path at a cosntant rate at 20 miles per hour. The cyclist stops to wait for the hiker 5 minutes after passing her, while the hike continues to walk at her constant rate. How many minutes must the cyclist wait until the hiker catches up?

Answer: 20

题目没读懂

骑车的再超过走路的人之后，等了5分钟，为何又问要等多久？

顶

请NN赐教！

汗，没说等了5分钟

说超过他5分钟之后，停下来等

(5/60)*20=5/3   cyclist在pass hiker后走的路

60*(5/3)*(1/4-1/20)=20      由于hiker在cyclist pass她后仍在走，所以要减去hiker的时间

如果不理解，也可以把5/3看成a,第二个式子就变成：60*（a/4-a/20）

谢谢两位，尤其是grace!很详细，我明白你们的意思了。

问题是出在对“The cyclist stops to wait for the hiker 5 minutes after passing her”的理解上，对吗？

考场上，一紧张，真不知道我会怎样。。。

狂汗。。。