Data Sufficiency

If xy2=1, is x>y?


1) -1<y<1
2) xy<0


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If xy2=1, is x>y?

1) -1<y<1
2) xy<0


In the original condition, there are 2 variables(x,y) and 1 equation(xy2=1), which should match with the number of equations. So you need 1 equation. For 1) 1 equation, for 2) 1 equation, which is likely to make D the answer.
For 1), in x=1/y2, it is always x>1, which is yes and sufficient.
For 2), in x=1/y2>0, x>0, y<0, which is yes and sufficient.
Therefore, the answer is D.


� For cases where we need 1 more equation, such as original conditions with "1 variable", or "2 variables and 1 equation", or "3 variables and 2 equations", we have 1 equation each in both 1) and 2). Therefore, there is 59 % chance that D is the answer, while A or B has 38% chance and C or E has 3% chance. Since D is most likely to be the answer using 1) and 2) separately according to DS definition. Obviously there may be cases where the answer is A, B, C or E.