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## Official Guide Explanation:Problem Solving #31

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: 31
Page: 156
Difficulty: 5 (Moderate)
Category 1: Word Problems > Rate Problems > Speed
Category 2: Algebra > Equations >

Explanation: This is a very popular type of GMAT question, and a tricky one. It's asking for time, and you can manipulate the traditional rate formula to give you time = ((dist)/(rate)). When working with words per minute, "distance" is a misnomer; it's really more like "amount of work" or, in this case, number of words. The question tells us that his number of words is y and his rate is x words per minute, so time = ((dist)/(rate)) = ((y)/(x)), choice (B). This method may seem more abstract (and perhaps for that reason uncomfortable) compared to plugging in values for the variables, but once you've mastered it, it is considerably faster than your other options.

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