number properties

Xbond · Posted: Sat Aug 30, 2008 7:09 am Post subject: number properties

If x <0, is Y >0 ?

(1) X/Y <0

(2) Y-X >0

I have some problems to define (2) for sure. Can you help me ?
At first look, I would say (2) is sufficient but i am not sure for 100%

II · Posted: Sat Aug 30, 2008 7:24 am Post subject:

So looking at the question stem ... we can see that this is testing our knowledge of positives and negatives.

If x < 0 (x is negative), is y > 0 (y positive) ?

(1) This is saying that x/y < 0 ... in other words ... x/y is negative. We know that neg/pos or pos/neg will always be a negative. In this case we know (from q-stem) that x is negative, so y must be positive. SUFF.

(2) This is saying that y-x > 0 ... in other words ... y-x is positive. This INSUFF to determine if y is positive or negative.
Let y=2 and x=(-3) ... so 2-(-3) = 5 ... which is positive. So this answers YES to the question, Is y>0 ?
Let y=(-2) and x=(-3) ... so (-2)-(-3) = -2+3 = 1 ... which is positive. This answers NO to the question, Is y>0 ?
We can also rearrange the inequality y-x>0 to y>x. And from this we can easily identify that we have INSUFF information to answer question. INSUFF.

Answer A.

Hope this helps.

Xbond · Posted: Sat Aug 30, 2008 8:20 am Post subject:

many thks