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## Official Guide Explanation:Problem Solving #6

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: 6
Page: 153
Difficulty: 4 (Moderately Easy)
Category 1: Algebra > Equations >
Category 2: Word Problems > Rate Problems > other
Category 3: Arithmetic > Ratio and Proportion >

Explanation: The best approach here is to work from the general objective--the number of paper clips in two cases--backward to things that are more simple. The number of paper clips in 2 cases is 2(\# per case), but we don't know the number per case. The number per case is c(\# per carton), but we don't know the number per carton. The number per carton is b(100), because we know there are 100 per box. If we know the number per carton is 100b, the number per case is c(100b), and the total number is 2(c(100b)), which we can rewrite more clearly as 200bc, choice (C).

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