Question

一辆车旅行时，先在一个半小时内行驶 $80$ 英里，然后在交通堵塞中停了 $30$ 分钟，接着在之后 $2$ 小时内行驶 $100$ 英里。这辆车在整个 $4$ 小时旅程中的平均速度是多少英里每小时？

On a trip, a car traveled $80$ miles in an hour and a half, then was stopped in traffic for $30$ minutes, then traveled $100$ miles during the next $2$ hours. What was the car's average speed in miles per hour for the $4$ -hour trip?

$45$

$50$

$60$

$75$

$90$

答案：A

知识点：路程、速度与时间

难度评级：930

解答：

这辆车总共行驶 $80 + 100 = 180$ 英里，总时间为 $1.5 + 0.5 + 2 = 4$ 小时，其中堵车停止时间也计入。

平均速度为 $\dfrac{180}{4} = 45$ 英里每小时。

所以正确答案是 A。

The car covered $80 + 100 = 180$ miles in total, over $1.5 + 0.5 + 2 = 4$ hours (the traffic stop still counts as time).

The average speed is $\dfrac{180}{4} = 45$ miles per hour.

Thus, the correct answer is A .

1992 AMC 8 第 18 题

答案：A

难度评级：930

解答：

其他年份的第 18 题