Is y – x positive?

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Is y – x positive?

by Vincen » Tue Dec 05, 2017 9:16 am
Is y - x positive?

(1) y > 0
(2) x = 1 - y

The OA is E.

Experts, may you help me? I don't have this DS question clear. Thanks in advanced.

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by GMATGuruNY » Tue Dec 05, 2017 9:22 am
Vincen wrote:Is y - x positive?

(1) y > 0
(2) x = 1 - y
Statement 1: y>0
Statement 2, rephrased: x+y = 1

Statements combined:
Case 1: x=0.1 and y=0.9
In this case, y-x = 0.9 - 0.1 = 0.8, so the answer to the question stem is YES.
Case 2: x=0.9 and y=0.1
In this case, y-x = 0.1 - 0.9 = -0.8, so the answer to the question stem in NO.
Since the answer is YES in Case 1 but NO in Case 2, the two statements combined are INSUFFICIENT.

The correct answer is E.
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