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explanation needed please

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explanation needed please

by T.K. » Thu May 22, 2008 7:00 pm
First GMAT prep from mba website, question #17:

In n and m are positive integers, what is the remainder when 3^(4n+2) is divided by 10.

1) n=2
2) m=1

.... Im so confused in terms of where m fits in this whole question...and why the answer is B: statement 2 ALONE is sufficient.

I'd appreciate any feedback.
Thanks!
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by amitansu » Fri May 23, 2008 1:24 am
Are you sure of the question put up here !!

Is it not 3^(4n+m)/10 or 3^(4m+2)/10 in stead of 3^(4n+2)/10 ?


Amit
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by T.K. » Fri May 23, 2008 6:00 am
I'm positive. I copied the question exactly as is from the software downloaded from mba.com - it's the first practice test :?
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by amitansu » Fri May 23, 2008 8:16 am
well , then it looks an impossible q for me....
According to q A should be choice here...


Amit
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by pranaysad » Sat May 24, 2008 6:55 pm
Should be A right because
3^8 = 81*81 and therefore the remainder is 1...

Just making sure.
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by VP_Tatiana » Tue May 27, 2008 8:20 pm
Yes, if this question is truly written correctly, the answer would be A.

However, your math is slightly off. If we use n=2 from statement 1, then we would have 3^((4*2) + 2) = 3^10.

Since that is one and only one number, which we could solve for if we wanted, this is enough information to figure out the remainder. Thus, statement 1 is sufficient.

Looking at statement 2, it only tells us something about a totally irrelevant variable m and it is not sufficient.

Since 1 is sufficient and 2 is not, the answer is A.
Tatiana Becker | GMAT Instructor | Veritas Prep
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