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## Official Guide Explanation:Problem Solving #95

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.

Question: 95
Page: 74
Difficulty: 4 (Moderately Easy)
Category 1: Word Problems > Mixture Problems >
Category 2: Arithmetic > Percents > other

Explanation: Find the number of defective parts in each shipment. If 5\of 120 parts were defective, that's (0.05)(120) or (1/20)(120) = 6 defective parts. If 10% of 80 parts were defective, that's (0.1)(80) = 8. Altogether, there are 6 + 8 = 14 defective parts and 120 + 80 = 200 total parts. The percent of parts that were defective, then, is (14/200) = (7/100) = 7%, choice (B).

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