[求助]GMATprep中一道数学题

nocturnetian

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

答案是20.

望好心人能告诉我具体的解题步骤

谢了

strawdog

the distance of the hiker and the cyclist is: (20-4)*(5/60)

the waiting time is (20-4)*(5/60)/4=1/3hour=20 minutes

lizhihuantu

5分钟车比人多走的距离是5/60*（20-4），用这个距离除以人的速度4为1/3小时，乘以60就是20minutes

借问下halfway到底是什么意思？MS PREP里面有道题里有，先谢过了

britney-gao

ding!!!!!

nocturnetian

thanks very much