Official Guide Explanation:
Problem Solving #49

 

 

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: 49
Page: 159
Difficulty: 5 (Moderate)
Category 1: Arithmetic > Properties of Integers > Other
Category 2: Algebra > Inequalities > other

Explanation: Given a compound inequality, you can simplify it like any other inequality, you just have to remember to do the same thing to all three parts instead of only two. In this case, since you're interested in n, solve for n:

1 < 5n + 5 < 25

-4 < 5n < 20

((-4)/5) < n < 4

Thus, the range for n limits it to four integers: 0, 1, 2, and 3, so the correct choice is (B).

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