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GMAT Tip of the Week for the week of October 29, 2012

This week’s GMAT tip* concerns GMAT Data Sufficiency, and specifically how to determine whether or not the statements are sufficient to solve for a particular variable. It’s called the “Solvability Rule,” and this short video will explain it in detail:

GMAT Tip of the Week: Sometimes a GMAT Data Sufficiency question will ask you whether or not you can solve for a particular variable (or some variation thereof: e.g. Is x>0?). Particularly when there are multiple equations and multiple variables in question, the “Solvability Rule” becomes a useful tool for evaluating the two Statements to determine sufficiency.

Specifically, The Solvability Rule says that you must have at least as many distinct equations as you have variables for the equations to be solvable. That is, if you are trying to figure out what x, y, and z are, you need at least three equations to do so. This rule is pretty straightforward to apply on certain GMAT data sufficiency questions (as in the example in the video above), but be sure to pay particular attention to the information given in the question stem itself. Often on harder questions, the GMAT testmakers will give additional information that essentially acts as an extra equation, making a statement sufficient that might not otherwise be.

* Each week, one of the GMAT experts at Dominate the GMAT shares a valuable GMAT test-taking tip, strategy, trick, or content item. These tips are designed to augment your GMAT study program and provide you with additional information that will help you improve your GMAT score.