GMAT prep question - is the OA wrong?

StarDust845

The question is simple.

If x > 0, is x > y ?

1) 7x - 4y = 3
2) 4x - 7y = 3

I believe the answer is D, but OA is different. Is my answer wrong?

Calista.

sujaysolanki · Posted: Sat Dec 15, 2007 5:14 pm Post subject:

Corrected to B ...trying picking numbers say put x =1 or 1/2 it will hold for stmt 1 ..not to for Hope this helps

Chiquito · Guest

Rephrase Statement 1:
X = (3/7) + (4/7)Y

#2:
X = (3/4) + (7/4)Y

1) is a maybe because there are some values X where Y is less than X, and some values X where Y is greater than X.
(ex: X=4/7 Y=1/4 or X=2 Y=11/4)

2) is a yes because no matter what value of X, it is always (7/4) times Y plus (3/4)

StarDust845 · Posted: Sun Dec 16, 2007 7:53 am Post subject:

Ah ha! I see what you are saying and then I approached my solution again and now I see the fallacy in my reasoning.

Here is how I solved (or thought that I solved) it.

The slope of the first equation is > 1. So I plotted the graph briefly and because slope is > 1, I assumed x is always less than y for x > 0.

For e.g assume a line with slope 1 passing through origin. The points in Quadrant I towards left of that line will always be x <y> y I extrapolated this fundamental to this GMAT question.. I assumed wrong obviously.

This can't be extrapolated. Thanks for your answer. This probably saved me from more mistakes, I would have made down the line.

Calista.

samirpandeyit62 · Posted: Sun Dec 16, 2007 8:32 pm Post subject:

If x > 0, is x > y ?

1) 7x - 4y = 3

i.e 7x > 4y or x > 4/7*y

so in this case x>y is possible, but it is also possibe that

x is less than y e.g x =0.8 *y

2) 4x - 7y = 3

i.e 4x > 7y

or x > 7/4*y

i.e x > 7/4*y > y

i.e x >y SUFF B

Hi Eric/Gabriel,
Is there a problem with inequality signs, whenever I put two inequality signs on successive lines, they somehow get merged into one.

StarDust845 · Posted: Mon Dec 17, 2007 8:46 am Post subject:

Beautiful! Thanks.

Calista.

gabriel · Posted: Mon Dec 17, 2007 9:51 am Post subject:

@ Samir, can u send Eric a PM stating the exact problem. Thanks.

Regards.