AMC 8 2015 Problem 3

AMC8 2015 年第 3 题

行程问题★☆☆☆☆

Jack and Jill are going swimming at a pool that is one mile from their house. They leave home simultaneously. Jill rides her bicycle to the pool at a constant speed of 10 miles per hour. Jack walks to the pool at a constant speed of 4 miles per hour. How many minutes before Jack does Jill arrive?

Jack 和 Jill 要去距离他们家 1 英里的游泳池去游泳。他们同时从家出发。Jill 以 10 英里每小时的速度骑车去泳池，Jack 以 4 英里每小时的速度走过去。那么 Jill 比 Jack 早到多少分钟？

A.5
B.6
C.8
D.9
E.10

正确答案 · Correct Answer

解析 · Solution

Solution 1

Using d=rt, we can set up an equation for when Jill arrives at the swimming pool: 1=10t Solving for

t

, we get that Jill gets to the pool in

\displaystyle \frac{1}{10}

of an hour, which is 6 minutes. Doing the same for Jack, we get that Jack arrives at the pool in

\displaystyle \frac{1}{4}

of an hour, which in turn is 15 minutes. Thus, Jill has to wait 15-6= minutes for Jack to arrive at the pool.

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