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## Official Guide Explanation:Problem Solving #27

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: 27
Page: 65
Difficulty: 4 (Moderately Easy)
Category 1: Arithmetic > Fractions >
Category 2: Arithmetic > Decimals >

Explanation: The easiest way to complete this problem and avoid careless mistakes by miscounting zeroes is to give all the fractions a common denominator. Multiply the first by 1,000 and the second by 100: ((3,000)/(100,000)) + (500/(100,000)) + (7/(100,000)) = ((3,507)/(100,000)). To find the decimal equivalent, see how many places the decimal in the denominator has to move to turn into 1. Since you have to move the decimal five places, you must do the same in the numerator: ((3,507)/(100,000)) = ((.03507)/1) = 0.03507, choice (E).

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