请教OG-404

zhangling2581

A square countertop has a square tile inlay in the center,leaving an untiled strip of unniform width around the tile. If the ratio of the tiled area to the untiled area is 25 to 39, which of the following could be the width, in inches, of the strip?

1.1+1/2  II.3  III.4+1/2


A. I only
B. II only
C. I and II only
D.I and III only
E. I , II, and III

Ans:E

Pls help me . Thanks.

himba

大正方形套小正方形的题目.

设大正方形边长是X，小正方形边长是Y，它们之间的条形围成的区域宽度是W，根据题意：

1）     Y平方/X平方=25/（25＋39）＝>  Y/X=5/8

2）    W=(X-Y)/2

解得，W=(3X)/16

由此可见，W什么数字都可以取。