Question

如图，平面由全等的正方形和全等的五边形铺成。被五边形覆盖的平面面积百分比最接近

The plane is tiled by congruent squares and congruent pentagons as indicated. The percent of the plane that is enclosed by the pentagons is closest to

$50$

$52$

$54$

$56$

$58$

答案：D

知识点：面积比铺砖百分数

难度评级：1530

解答：

考虑一个重复的 $3\times3$ 方块，共九个小正方形；其中四个不属于五边形，所以五边形覆盖的比例为 $1-\dfrac49=\dfrac59\approx55.6\%$ 。

这个百分比最接近 $56$ 。所以正确答案是 D。

Consider a repeating $3\times3$ block of nine small squares. Four of these nine squares are not part of the pentagons, so the pentagons cover $1-\dfrac49=\dfrac59\approx55.6\%$ of the area.

This is closest to $56.$ Thus, the correct answer is D.

2001 AMC 10 第 18 题

答案：D

难度评级：1530

解答：

其他年份的第 18 题