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## Official Guide Explanation:Problem Solving #225

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: 225
Page: 184
Difficulty: 6 (Moderately Difficult)
Category 1: Arithmetic > Fractions >
Category 2: Word Problems > Other >

Explanation: It may be easier to think of this pipe as 12 yards in length, since then the markings in fourths and thirds will have integer values instead of fractional ones. The markings in fourths will come at 3, 6, and 9 yards. The markings in thirds will be at 4 and 8 yards. Altogether, there will be markings at 3, 4, 6, 8, and 9 yards. So, in the 12 yard pipe, there are pieces between markings of 3, 1, 2, 2, 1, and 3 yards. We only need to look at one of each length, and divide them by 12 to adjust back to a 1 yard pipe. Those are (3/12), (1/12), and (2/12), or, reduced: (1/4), (1/12), and (1/6), choice (D).

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