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## Official Guide Explanation:Data Sufficiency #120

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: 120
Page: 161
Difficulty: 6 (Moderately Difficult)
Category 1: Algebra > Absolute Value >
Category 2: Algebra > Inequalities > other
Category 3: Arithmetic > Fractions >

Explanation: a - b and b - a will never have the same sign, so the only way for the inequality in the question to be true is if a - b is negative, which means that b must be greater than a. In other words, the question can be rewritten as: Is b greater than a?

Statement (1) is sufficient, as it answers that question directly: b is greater than a. Statement (2) is insufficient: all it tells us is that the positive difference between the two variables is greater than 1. It contains no information about which variable is bigger. Choice (A) is correct.

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