AMC8 2006

AMC8 2006 · Q4

AMC8 2006 · Q4. It mainly tests Transformations.

Initially, a spinner points west. Chenille moves it clockwise $2 \frac{1}{4}$ revolutions and then counterclockwise $3 \frac{1}{4}$ revolutions. In what direction does the spinner point after the two moves?

最初，转盘指向西。Chenille 将其顺时针转动 $2 \frac{1}{4}$ 圈，然后逆时针转动 $3 \frac{1}{4}$ 圈。转盘最终指向哪个方向？

(A) north 北

(B) east 东

(D) west 西

(E) northwest 西北

Answer

Correct choice: (B)

正确答案：（B）

Solution

(B) Ignore the number of complete revolutions because they do not affect direction. One-fourth of the distance around the circle clockwise from west is north. Three-fourths of the distance counterclockwise around the circle from north is east. Chenille’s spinner points east.

（B）忽略完整转了多少圈，因为这不会影响方向。从西向顺时针沿圆周走四分之一圈会到达北。从北向逆时针沿圆周走四分之三圈会到达东。Chenille 的转盘指向东。

Topics

GE.011 Transformations