Official Guide Explanation:
Problem Solving #50




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.

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


Solution and Metadata

Question: 50
Page: 159
Difficulty: 5 (Moderate)
Category 1: Algebra > Absolute Value >

Explanation: An expression inside absolute value signs can never be negative, so we're looking for the value of 23 - 5y that is closest to zero. Given that we're working with small numbers, the best way to find this is some simple trial and error. Since 5(5) = 25, that will get us close to zero--if y = 5, 23 - 5y= - 2, so the absolute value is 2. If y is larger, the value of 23 - 5y gets smaller, so the absolute value gets larger. y could also be smaller; if y = 4, 23 - 5y = 3. That's not as close to zero; the absolute value is greater than the absolute value when y = 5. Thus, the least possible value of |23 - 5y| is 2, choice (B).

Click here for the full list of GMAT OG12 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.