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If xy < 4, is x < 2?

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by M7MBA » Wed May 16, 2018 1:30 am

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If xy < 4, is x < 2?

(1) y > 1

(2) y > x

The OA is B.

I am confused here. I don't know why the first statement is not sufficient and I don't know how to show that the second one is. Can someone clarify this doubt? Thanks.
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Source: — Data Sufficiency |

by GMATGuruNY » Wed May 16, 2018 2:11 am
M7MBA wrote:If xy < 4, is x < 2?

(1) y > 1

(2) y > x
Statement 1:
Case 1: y=2 and x=1, with the result that xy < 4
In this case, x<2, so the answer to the question stem is YES.
Case 2: y=3/2 and x=2, with the result that xy < 4
In this case, x=2, so the answer to the question stem is NO.
Since the answer is YES in Case 1 but NO in Case 2, INSUFFICIENT.

Statement 2:
Test whether it's possible that x=2.
Substituting x=2 into xy < 4, we get:
2y < 4
y < 2.
Not possible:
Since x=2 and y < 2, the condition that y > x is not satisfied.
For the value of y to increase so that y > x, the value of x must DECREASE.
Thus, x < 2.
SUFFICIENT.

The correct answer is B.
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