AMC8 1990

AMC8 1990 · Q23

AMC8 1990 · Q23. It mainly tests Rates (speed).

The graph relates the distance traveled [in miles] to the time elapsed [in hours] on a trip taken by an experimental airplane. During which hour was the average speed of this airplane the largest?

该图表示实验飞机一次飞行中行驶距离[英里]与经过时间[小时]的关系。在哪一小时该飞机的平均速度最大？

(A) first (0-1) 第一 (0-1)

(B) second (1-2) 第二 (1-2)

(D) ninth (8-9) 第九 (8-9)

(E) last (11-12) 最后一 (11-12)

Answer

Correct choice: (B)

正确答案：（B）

Solution

Answer (B): The rate will be the largest when the graph is the “steepest”. During the second hour the distance traveled is about $500$ miles, so the average speed during that hour is about $500$ mph. For the other hours, the speeds are less than $350$ mph.

答案（B）：当图像最“陡”时，速度最大。在第二个小时内，行驶的距离约为 $500$ 英里，因此该小时的平均速度约为 $500$ 英里/小时。其余时间段的速度都小于 $350$ 英里/小时。

Topics

AR.007 Rates (speed)