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## Official Guide Explanation:Data Sufficiency #84

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: 84
Page: 280
Difficulty: 5 (Moderate)
Category 1: Algebra > Linear Equations-Two Unk >
Category 2: Arithmetic > Descriptive Statistics > Average

Explanation: The average of j and k is ((j + k)/2), so all we need is the sum of j and k. Statement (1) is sufficient: to write this statement as an equation looks like this:

((j + 2 + k + 4)/2) = 11

j + 2 + k + 4 = 22

j + k + 6 = 22

j + k = 16

Given the sum of j and k, you can find the average. Statement (2) is also sufficient:

((j + k + 14)/3) = 10

j + k + 14 = 30

j + k = 16

Again, we're able to find the sum of j and k. Note that the individual values of j and k are not important; we only need the sum to answer the question. Both statements are sufficient, so choice (D) is correct.

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