Official Guide Explanation:
Problem Solving #179

 

 

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.

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Solution and Metadata

Question: 179
Page: 177
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Ratio and Proportion >

Explanation: This is more like a data sufficiency question than a problem solving question. If you know the ratio between two quantities and then you add an absolute number to both, you don't know the resulting ratio. Algebraically, the original ratio of (3/4) indicates that the quantities were ((3x)/(4x)). After adding 5, the quantities are ((3x + 5)/(4x + 5)), which can't be simplified to a ratio without variables. Thus, the answer is (E).

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