GMAT Prep algebra

vinviper1 · Posted: Wed Apr 23, 2008 11:23 am Post subject: GMAT Prep algebra

Thanks much!

lunarpower · Posted: Thu Apr 24, 2008 1:28 am Post subject:

wait what?

something is seriously wrong here, as elementary number picking is quick to show.

first off, the 2's clearly cancel, so get rid of them.

if we let x = 2 and y = 1/2, then the expression is (5/2)^2 / (3/2)^2, which is 25/9 = 2.77777..., an answer that is clearly not listed. worse yet, plugging in other numbers leads to other answer choices.

incidentally, the only numbers that satisfy the initial constraint (xy = 1) and actually give the answer 16 are plus or minus (√15)/5 and (√15)/3 - two numbers that, i can confidently say, no one is going to pick anytime soon.

lunarpower · Posted: Thu Apr 24, 2008 1:45 am Post subject:

wait, uh, well, i made up a problem that looks at least somewhat like this one, with the desired solution.

here you go:

simplyjat · Posted: Thu Apr 24, 2008 2:30 am Post subject:

This question is a mistake in GMATPrep, The original intent of the question is to ask

If XY = 1
Than what is the value of (2^[(x+y)^2])/(2^[(x-y)^2]) ?
Which simplifies to
(2^(x^2))*(2^(y^2))*(2^(2xy)) / (2^(x^2))*(2^(y^2))*(2^(-2xy))
=> (2^(2xy)) / (2^(-2xy))
=> (2^(4xy))
=> (2^(4*1))
=> 2^4
=> 16

lunarpower · Posted: Thu Apr 24, 2008 3:22 am Post subject:

simplyjat · Posted: Thu Apr 24, 2008 3:46 am Post subject:

Actually the correct question is stated in OG. I can't remember the exact question number, but I remember solving the question from one of the books...

resilient · Posted: Sun Apr 27, 2008 2:42 am Post subject: pk

So do we need to worry about these test blunders on the real thing?

Sunny22uk · Posted: Sun Apr 27, 2008 8:58 pm Post subject:

Yeah, Iwas actually thinking that there is something wrong with the question and I read the posts below. I remember solving this question as an exponential question somewhere

simplyjat · Posted: Sun Apr 27, 2008 10:18 pm Post subject:

Yesterday, I was giving the GMAT prep and the same question popped up for me. But amazingly the formatting was correct! It seems that there can be a problem with your GMATPrep setup.

vinviper1 can you let us know the setup: Operating System and Java Run-time version. To see the version of windows right-click "My computer" and select "Properties". To see the version of Java run time environment, on command prompt type "java -version".

It would be really helpful for other people...

vinviper1 · Posted: Mon Apr 28, 2008 11:38 am Post subject:

Hey guys,

Wow that is nuts! I am not home to check out the Java info, but this was done on a Windows XP Professional system. Thanks for the info.

simplyjat · Posted: Mon Apr 28, 2008 12:35 pm Post subject:

I hope that with Windows XP Professional system you mean with the latest SP2 and all the updates/patches...