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Official Guide Explanation:Data Sufficiency #139

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: 139
Page: 285
Difficulty: 6 (Moderately Difficult)
Category 1: Arithmetic > Fractions >
Category 2: Arithmetic > Decimals >
Category 3: Arithmetic > Properties of Integers > Remainder

Explanation: Whether or not a decimal is terminating depends largely on the denominator: if the denominator is 2, for instance, the result will be an integer or a decimal of .5. (Other denominators of this type are 4, 5, 8, and 10.) However, any denominator that is a multiple of 3 will either be an integer or a non - terminating decimal, such as 0.33‾ .

Statement (1) is insufficient, as it provides no information about the denominator. Statement (2) is sufficient: if the denominator is 4, the decimal is either .0, .25, .5, or .75. In any of those cases, it is terminating. Choice (B) is correct.

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