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## Official Guide Explanation:Problem Solving #147

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: 147
Page: 173
Difficulty: 6 (Moderately Difficult)
Category 1: Geometry > Triangles > Pythag
Category 2: Geometry > Triangles > Multiple figures
Category 3: Word Problems > Geometry Problems >

Explanation: If you call the point where the right angle is located point Q, then triangle VQR is a right triangle of which two of the sides are known. We know that side VQ is 5 and the hypotenuse, VR, is 10. Thus, we can solve for the distance QR. If we call QR x, then 52 + x2 = 102 , or 25 + x2 = 100, or x2 = 75, or x = 5 rt[3]. Since RS (that's what we're looking for, after all!) is the difference between QS and QR, we can solve for it by subtraction: 10 - 5 rt[3], choice (A).

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