Advanced PS Question Pack1 Question

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Advanced PS Question Pack1 Question

by bpolley00 » Tue Aug 13, 2013 5:45 pm
For a certain set of numbers, If x is in the set, then x-3 is also in the set. If the number 1 is in the set, which of the following must also be in the set?
I. 4
II. -1
III. -5

I only
II only
III only
I and II
II and III

GMAT Question Pack Explanation: It is given that 1 is in the set. Therefore 1-3= -2 is in the set. Since we know -2 is in the set then -5 is also in the set. This set doesn't contain 4 or -1!. Therefore it is not true 4 or -1 must be in the set.

I was hoping GMAT would address an issue I found with this particular problem.
The general issue is this: The set doesn't necessarily need ANY of the numbers listed above following the logic in the answer explanation. Here is an example Let's say X = 1 and therefore the second variable x-3 would equal -2. The set could merely be (1,-2), thus the answer would be none.No where in the question does it implicitly state the set is more than 2 numbers nor does it state that it must be continuous. However, following the question and assuming that it needs to have one, I believe the better answer would be I. Was X=4, therefore X-3 = 1 so the set would have to be {4,1}

Any thoughts on this? I bought the question pack and it has been immensely helpful, so thank you; however, I just spotted this question and there has been a few questions that I have found kind of worrisome so I appreciate your response on this.

-BP

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by OfficialGMAT » Wed Aug 14, 2013 11:17 am
Hello, BP.I have passed your question on to our GMATPrep team. If you send an email to gmatprep@mba.com they can get back to you with a detailed response.

Thank you!

Rebecca
Leah
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by bpolley00 » Wed Aug 14, 2013 4:47 pm
Rebecca,

The e-mail has been sent. I have my test tomorrow so it doesn't really matter much for me; however, I thought it may be helpful to other students! Thanks so much for your time.

Sincerely,

BP

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by OfficialGMAT » Thu Aug 15, 2013 5:28 am
Thanks for letting us know. I know they are looking into this particular question right now. We always appreciate feedback.

Rebecca
Leah
Official GMAC Representative

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