Official Guide Explanation:
Problem Solving #15




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Solution and Metadata

Question: 15
Page: 63
Difficulty: 4 (Moderately Easy)
Category 1: Geometry > Quadrilaterals >
Category 2: Word Problems > Geometry Problems >
Category 3: Arithmetic > Percents > other

Explanation: If the rug is 9 by 12, the area of the rug is 9(12). If 60\of the floor is covered by that rug, ((6/10))f = 9(12). To solve: f = (9)(12)((10/6)) = (9)(2)(10) = 180, choice (C). Note that you never needed to find the area of the rug--in fact, it was easier to do the problem without taking that intermediate step. Often, right after doing multiplication, you'll find yourself doing division with the same number. It takes some practice to know when to avoid multiplying, but try it out--worst case scenario, you'll just have to multiply later on.

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