Official Guide Explanation:
Problem Solving #89




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Solution and Metadata

Question: 89
Page: 73
Difficulty: 4 (Moderately Easy)
Category 1: Arithmetic > Percents > Percent Change
Category 2: Word Problems > Discount >

Explanation: This is a great question to assign values to the unknown quantities. If the length is 5 and the width is 20, the original area is 5(20) = 100. (It's important to pick simple numbers to work with, and ones that can be easily increased by 20%.) When each dimension is increased by 20%, the length becomes (1.2)(5) = 6, and the width becomes (1.2)(20) = 24. Now, the area is 24(6) = 144. The percent increase then, is given by ((increase)/(original)) = ((144 - 100)/100) = (44/100) = 44%, choice (E).

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