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Re: Given x = y + z. Is x > y ? 1) y > 0 2) z > 0
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15 Jun 2018, 10:43
Top Contributor
gmatbusters wrote:
Given x = y + z. Is x > y ?
1) y > 0 2) z > 0
Great question!
Given: Given x = y + z
Target question:Is x > y ? This is a good candidate for rephrasing the target question.
Aside: the video below has tips on rephrasing the target question
Take x > y, and subtract y from both sides to get: x - y > 0 So, asking Is x > y? is the SAME AS asking Is x - y > 0?
REPHRASED target question:Is x - y >?
Statement 1: y > 0 There are several values of x, y and z that satisfy statement 1. Here are two: Case a: x = 3, y = 2 and z = 1 (this satisfies the given condition that x = y + z. In this case, x - y = 3 - 2 = 1. So, the answer to the REPHRASED target question is YES, x - y IS greater than 0 Case b: x = 2, y = 3 and z = -1 (this satisfies the given condition that x = y + z. In this case, x - y = 2 - 3 = -1. So, the answer to the REPHRASED target question is NO, x - y is NOT greater than 0 Since we cannot answer the REPHRASED target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: z > 0 It's given that x = y + z This means that x - y = z Since statement 1 tells us that z > 0, then it is the case that x - y > 0 PERFECT!! The answer to the REPHRASED target question is YES, x - y IS greater than 0 Since we can answer the REPHRASED target question with certainty, statement 2 is SUFFICIENT
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55% (00:58) correct 
