Question

Josh 和 Mike 相距 $13$ 英里。昨天 Josh 开始骑车去 Mike 家。稍后 Mike 开始骑车去 Josh 家。他们相遇时，Josh 骑行的时间是 Mike 的两倍，速度是 Mike 的五分之四。相遇时 Mike 骑了多少英里？

Josh and Mike live $13$ miles apart. Yesterday Josh started to ride his bicycle toward Mike's house. A little later Mike started to ride his bicycle toward Josh's house. When they met, Josh had ridden for twice the length of time as Mike and at four-fifths of Mike's rate. How many miles had Mike ridden when they met?

$4$

$5$

$6$

$7$

$8$

答案：B

知识点：路程、速度与时间一次方程

难度评级：1240

解答：

设 Mike 骑了 $m$ 英里。Josh 的速度是 Mike 的 $\frac{4}{5}$ ，时间是 Mike 的 $2$ 倍，所以 Josh 的距离为 $\frac{8}{5}m$ 。两人合计骑了 $13$ 英里，因此 $m + \frac{8}{5}m = \frac{13}{5}m = 13$ ，得到 $m = 5$ 。

所以正确答案是 B。

Let Mike ride $m$ miles. Josh rides $\frac{4}{5}$ the rate for $2$ times the time, so Josh's distance is $\frac{8}{5}m.$ Together they cover $13,$ so $m + \frac{8}{5}m = \frac{13}{5}m = 13,$ giving $m = 5.$

Thus, the correct answer is B.

2005 AMC 10A 第 7 题

答案：B

难度评级：1240

解答：

其他年份的第 7 题