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Official Guide Explanation:Data Sufficiency #88

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: 88
Page: 280
Difficulty: 5 (Moderate)
Category 1: Algebra > Linear Equations-Two Unk >
Category 2: Arithmetic > Percents > other

Explanation: The question gives us a formula:

m + r + h = 12,000

We're looking for the value of r.

Statement (1) is insufficient. It does give us another equation:

r + h = (1/3)m

With that, we can substitute (1/3)m for r + h in the original equation. We can then solve for m, but that doesn't help us isolate r.

Statement (2) is sufficient. It gives us an equation as well:

r = 0.2(m + h)

Or:

5r = m + h

We can substitute 5r for m + h in the original equation:

r + 5r = 12,000

6r = 12,000

r = 2,000

Choice (B) is correct.

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