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## Official Guide Explanation:Data Sufficiency #37

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: 37
Page: 276
Difficulty: 4 (Moderately Easy)
Category 1: Word Problems > Other >
Category 2: Arithmetic > Percents > other

Explanation: If we use the first letter of "selling price," "cost," and "markup," we can express the first sentence as follows:

s = c + m

We want to know what percent the markup is of the selling price, or:

((m)/(s)) * 100%

Statement (1) is sufficient. If the markup is 25% of the cost, the cost is 4 times the markup, or 4m. Thus:

s = c + m

s = 4m + m = 5m

If s = 5m, then ((m)/(s)) * 100 = ((m)/(5m)) * 100% = 20%.

Statement (2) is insufficient. It gives us one number, but no way to determine relationships between any two of the three amounts. Choice (A) is correct.

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