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## Official Guide Explanation:Problem Solving #154

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: 154
Page: 174
Difficulty: 5 (Moderate)
Category 1: Word Problems > Measurement Problems >
Category 2: Word Problems > Rate Problems > Speed
Category 3: Arithmetic > Ratio and Proportion >

Explanation: The question tells you how long it takes for the pool to fill (3/5) of the way, and it wants to know how long it will take to fill the remaining (2/5). This is a ratio, so set it up like one. ((amount)/(time)) = (((3/5))/8) = (((2/5))/(x)). Cross - multiply: (3/5)(x) = (2/5)(8), or 3x = 16, or x = (16/3) = 5(1/3)= 5 hours, 20 minutes, choice (B).

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