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## Official Guide Explanation:Data Sufficiency #97

Background

This is just one of hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Review (12th 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: 97
Page: 281
Difficulty: 5 (Moderate)
Category 1: Algebra > Exponents >
Category 2: Algebra > Inequalities > Negatives

Explanation: Statement (1) is sufficient. If x2 > 9, then either x > 3 or x< - 3. Since we know that x is negative, it must be latter: x< - 3. That answers the question directly.

Statement (2) is insufficient. We can take the cube root of both sides:

x< 3rt[ - 9]

You aren't expected to know the exact cube root of -9, so approximate. The cube root of -8 would be -2, so the cube root of -9 must be very close to -2. To keep it simple, let's say -2.1:

x< - 2.1

The value of x could be either greater or less than -3. Choice (A) is correct.

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