Positive/Negative Number properties

[jessicamuniz]

Hi guys,
Can somebody explain it to me please.

Is x > y ?
1) 9x=4y
2)x > -y

Thanks a lot [/quote]

[2008]

9x=4y is sufficient to answer, hence either A or D

x>-y is not sufficient, hence A.

[kshin78]

9x=4y is sufficient to answer, hence either A or D

x>-y is not sufficient, hence A.

Wouldn't it be E because:

9x = 4y ----> x = (4/9)y

here when x = -4/9 y= -1 x> y

when x = 4/9 y=1 x<y

therefore A is not sufficient.

B is also not sufficient

Thus, E.

What's the oA?

[parallel_chase]

The answer should be E.

Statement I

9x=4y
x=4
y=9
36=36, x<y

x=-4
y=-9
-36 = -36, x>y

Hence Insufficient.

Statement II

x>-y

It does not tell us anything about positive y, therefore insufficient.


Hence the answer is E.

Whats the OA?

[jessicamuniz]

Hi guys it is me again.
Thanks for all the answers and I also agree with you and I say that the answer is letter E.
However, this problem comes form the GMAT Kaplan book and in the answers it actually said that the right answer is letter C.
I read the explainations already but I still do not get it.
What do you think about this ???

[arorag]

The answer should be E.

Statement I

9x=4y
x=4
y=9
36=36, x<y

x=-4
y=-9
-36 = -36, x>y
SEE the second condition

Hence Insufficient.

Statement II

x>-y

It does not tell us anything about positive y, therefore insufficient.


Hence the answer is E.

It should be C. See second condition

Whats the OA?

[kris610]

I agree with C.

First says, both x and y could be 0, in which case it is a NO. For +ve y, x <y and -ve y, x > y.

Second statement by itself is not sufficient.

Now, from (1), we have x = (4/9) y. From 2, we have (x+y) > 0. Put these together, and you get y>0, in which case x<y.

[BlueRain]

We can all agree that neither statements is sufficient alone, thus it comes down to C or E.

9x = 4y
x > -y

multiple the second equation by 9
9x > -9y
4y > -9y (substitute 9x with 4y according to 1st equation)
y > 0
x > 0 (x = 4/9y and y>0)
if they are both positive, x = 4/9y must be x < y.

C. Hope this helps.