Official Guide Explanation:
Problem Solving #175

 

 

Background

This is just one of hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Quantitative Review (2nd 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.

Click here for an example of the PDF booklets. Click here to purchase a PDF copy.

 

Solution and Metadata

Question: 175
Page: 85
Difficulty: 6 (Moderately Difficult)
Category 1: Geometry > Quadrilaterals >
Category 2: Arithmetic > Ratio and Proportion >
Category 3: Word Problems > Geometry Problems >

Explanation: This question is deceptive, but not as hard as it looks. If there are no restraints on what the width of the strip could be (for instance, that the length or width of the countertop or the inlay must be an integer), then the width could be any number. Simply knowing the ratio of the tiled area to the untiled area tells us nothing at all about the possible lengths for the strip. It's like a Data Sufficiency statement that is automatically insufficient: given a ratio, you don't know anything about actual numbers. With that in mind, any of the three numbers could be the width of the strip, so the correct answer is (E).

Click here for the full list of GMAT Quant Review explanations.

 

You should follow me on Twitter. While you're at it, take a moment to subscribe to GMAT Hacks via RSS or Email.

Total GMAT Math

The comprehensive guide to the GMAT Quant section. It's "far and away the best study material available," including over 300 realistic practice questions and more than 500 exercises!
Click to read more.