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## Official Guide Explanation:Problem Solving #100

Background

This is just one of hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Quantitative Review (2nd ed.). Click the links on the question number, difficulty level, and categories to find explanations for other problems.

These are the same explanations that are featured in my "Guides to the Official Guide" PDF booklets. However, because of the limitations of HTML and cross-browser compatibility, some mathematical concepts, such as fractions and roots, do not display as clearly online.

Question: 100
Page: 74
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Percents > other
Category 2: Arithmetic > Percents > Percent Change
Category 3: Word Problems > Discount >

Explanation: This is a great question to use an actual number instead of a variable. Say that Carlos earned \$100 last year. If he saved 10% of that, he saved 10%(\$100) = \$10. If he earned 5 percent more this year, that's \$100 + 5%(\$100) = \$100 + \$5 = \$105. 12 percent of that will take a little work, but it works out to \$12.60. The question is asking, then, what percent \$12.60 is of \$10. Doing the math isn't necessary: since \$10 is such a simple number to work with, it's evident that the correct answer is choice (C), 126%.

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