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## Official Guide Explanation:Problem Solving #186

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: 186
Page: 178
Difficulty: 5 (Moderate)
Category 1: Word Problems > Other >
Category 2: Arithmetic > Fractions >

Explanation: This is a good question in which to assign a value to the unknown quantities. Say that the capacity of X is 6, which makes the capacity of Y 12. (The numbers were chosen to be easily divisible by 2 and 3, the denominators of the fractions we're about to work with.) So, drum X contains 3 gallons of oil, while drum Y contains (2/3)(12) = 8 gallons. If the contents of drum X are poured into drum Y, that's a total of 8 + 3 = 11 gallons in drum Y, out of a capacity of 12. Thus, drum Y is filled to (11/12) of capacity, choice (C).

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