Question

Cassie 上午 $8:30$ 从 Escanaba 骑车前往 Marquette，速度恒定为每小时 $12$ 英里。Brian 上午 $9:00$ 从 Marquette 骑车前往 Escanaba，速度恒定为每小时 $16$ 英里。他们骑在 Escanaba 和 Marquette 之间同一条 $62$ 英里的路线上。上午几点他们相遇？

Cassie leaves Escanaba at $8:30$ AM heading for Marquette on her bike. She bikes at a uniform rate of $12$ miles per hour. Brian leaves Marquette at $9:00$ AM heading for Escanaba on his bike. He bikes at a uniform rate of $16$ miles per hour. They both bike on the same $62$ -mile route between Escanaba and Marquette. At what time in the morning do they meet?

$10:00$

$10:15$

$10:30$

$11:00$

$11:30$

答案：D

知识点：路程、速度与时间

难度评级：1270

解答：

Brian 开始骑车时，Cassie 已经骑了 $\dfrac{1}{2}\cdot 12=6$ 英里。因此两人相距 $62-6=56$ 英里。

他们合起来以每小时 $12+16=28$ 英里的速度缩短距离。因此他们在上午九点后 $56\div 28=2$ 小时相遇。

所以他们在上午 $11:00$ 相遇。

所以正确答案是 D。

By the time Brian starts biking, Cassie has already traveled $\dfrac{1}{2}\cdot 12=6$ miles. This means that Cassie and Brian are then $62-6=56$ miles apart.

Together, they close the distance at $12+16=28$ miles per hour. This means that they meet $56\div 28=2$ hours after 9:00 AM.

This means that they meet at $11:00$ AM.

Thus, D is the correct answer.

2006 AMC 8 第 13 题

答案：D

难度评级：1270

解答：

其他年份的第 13 题