AMC8 2011

AMC8 2011 · Q13

AMC8 2011 · Q13. It mainly tests Area & perimeter, Ratios in geometry.

Two congruent squares, ABCD and PQRS, have side length 15. They overlap to form the 15 by 25 rectangle AQRD shown. What percent of the area of rectangle AQRD is shaded?

有两个边长为15的相符正方形ABCD和PQRS，它们重叠形成如图所示的15×25矩形AQRD。矩形AQRD面积中有多少百分比是阴影部分？

(A) 15 15

(B) 18 18

(D) 24 24

(E) 25 25

Answer

Correct choice: (C)

正确答案：（C）

Solution

The length of BP is 5. the ratio of the areas is $\dfrac{5\cdot 15}{25\cdot 15}=\dfrac{5}{25}=20\%$

BP的长度为5。面积比为$\dfrac{5\cdot 15}{25\cdot 15}=\dfrac{5}{25}=20\%$

Topics