Official Guide Explanation:
Data Sufficiency #5

 

 

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.

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Solution and Metadata

Question: 5
Page: 273
Difficulty: 4 (Moderately Easy)
Category 1: Word Problems > Other >
Category 2: Geometry > Lines >

Explanation: It might be helpful to draw a diagram for this question. Even better, view it as a system of linear equations. Statement (1) tells you that L - J = 21, where L and J are the mile markers at exits L and J. It tells you nothing about K, so it's insufficient. Statement (2): M - K = 26. Nothing about L, so it's insufficient.

Taken together, the statements are still insufficient. You have two equations with four variables: that's not enough to solve for any of the variables. Since there are no variables in common between the two equations, there's no chance you can combine them in some way to find the value of K - L. Choice (E) is correct.

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