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## Official Guide Explanation:Data Sufficiency #75

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: 75
Page: 158
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Descriptive Statistics > Average
Category 2: Arithmetic > Percents > other
Category 3: Algebra > Linear Equations-Two Unk >

Explanation: Statement (1) is sufficient: if Team A played 25 games, then it played 5 games after the first 20. Since it won 10 of the first 20 games and all of the remaining 5 games, it won a total of 15 games. Statement (2) is also sufficient. The percent of games Team A won is given by ((10 + r)/(20 + r)), where r is the number of remaining games after the first 20. If ((10 + r)/(20 + r)) = 0.6, you can solve for r, then add that number to 10 to find the total number of games Team A won. Choice (D) is correct.

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