jasontomonaga
 
等　级：黄金词友

              积　分：2281分

        专家分：49分

看我其他帖子
看我的日志

        看我该帖回复

主题：[The Official SAT Question of the Day™] December 26th Friday

收藏本贴 | 好友分享 | 推广拿分

点击:331 | 回复:2 | 标签:

The length of rectangle S is 20 percent longer than the length of rectangle R, and the width of rectangle S is 20 percent shorter than the width of rectangle R. The area of rectangle S is
A. 20% greater than the area of rectangle R
B. 4% greater than the area of rectangle R
C. equal to the area of rectangle R
D. 4% less than the area of rectangle R
E. 20% less than the area of rectangle R

19
来顶一下

2
快速回复

复制地址

SAT题目：http://apps.collegeboard.com/qotd/question.do

楼主 Date: 2008-12-26 20:06:12

jasontomonaga

看我其他帖子
看我的日志

		看我该帖回复

Hint : Represent the length and width of Rectangle R as x and y. Then you can represent the dimensions of rectangle S in terms of x and y. Both areas can then be represented in terms of x and y, and this will allow you to compare the areas of the two rectangles.

沙发 Date: 2008-12-26 21:12:00

jasontomonaga

看我其他帖子
看我的日志

		看我该帖回复

Correct Answer: D

Here's Why: Represent the length and width of rectangle R as x and y. Then the area of R is xy. The length of rectangle S is 20% longer than x, which is x + 0.20x, or 1.2x. Similarly, the width of S is y – 0.20y, or 0.8y. The area of S is (1.2x)(0.8y), which simplifies to 0.96xy. From this it follows that the area of rectangle S is 4% less than the area of rectangle R.
Difficulty: Hard
Question Type: Standard Multiple Choice
(Mathematics)

板凳 Date: 2008-12-26 21:12:58