Official Guide Explanation:
Problem Solving #1




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: 1
Page: 152
Difficulty: 3 (Very Easy)
Category 1: Word Problems > Rate Problems > other
Category 2: Arithmetic > Ratio and Proportion >

Explanation: The question is looking for the difference between actual spending and budgeted spending for a period of four months. We're given the first, and need to find the second. To find the second, we need the monthly rate: (($12,600)/12), but there's no reason to solve for that just yet. If that's the monthly rate, the total budgeted spending for four months in 4((($12,600)/12)), which we can simplify to (($12,600)/3). That's $4,200, so we can finish the problem by subtracting $4,200 from $4,580 for the correct answer of $380, choice (A).

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.