Official Guide Explanation:
Problem Solving #20

 

 

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: 20
Page: 155
Difficulty: 3 (Very Easy)
Category 1: Arithmetic > Fractions >
Category 2: Arithmetic > Ratio and Proportion >

Explanation: To simplify a ratio, you can manipulate one side any way you like as long as you do the same to the other side. (Ratios are fractions, so you can treat them the same way.) Since all of the answer choices contain integers, you'll want to change (1/3) into an integer. Thus, multiply both sides of 2:(1/3) by 3: 2(3):3((1/3)) = 6:1, choice (A).

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