Question

Josh 和 Mike 相距 $13$ 英里。昨天 Josh 先骑自行车朝 Mike 家出发，稍后 Mike 也骑车朝 Josh 家出发。他们相遇时，Josh 骑车的时间是 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、速度与时间比与比例

难度评级：1270

小提示：

对每个人，路程等于速度乘以时间。

Distance equals rate times time for each rider

大提示：

Josh 的路程是 Mike 路程的 $\dfrac{4}{5} \cdot 2 = \dfrac{8}{5}$ 。

Josh’s distance is $\dfrac{4}{5} \cdot 2 = \dfrac{8}{5}$ of Mike’s distance

解答：

因为路程等于速度乘以时间，Josh 骑的距离是 Mike 的 $\dfrac{4}{5} \cdot 2 = \dfrac{8}{5}$ 。

设 Mike 骑了 $m$ 英里，则 $13 = m + \dfrac{8}{5}m = \dfrac{13}{5}m\text{，}$ 所以 $m = 5$ 。

所以正确答案是 B。

Since distance is rate times time, Josh rode $\dfrac{4}{5} \cdot 2 = \dfrac{8}{5}$ as far as Mike.

Let $m$ be the miles Mike rode. Then $13 = m + \dfrac{8}{5}m = \dfrac{13}{5}m,$ so $m = 5.$

Thus, the correct answer is B.

2005 AMC 12A 第 6 题

答案：B

难度评级：1270

小提示：

大提示：

解答：

其他年份的第 6 题