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by gmatutor » Thu Oct 02, 2008 4:07 am
n is greater than or equal to 2 and n is less than or equal to 15.

So there are an equal number of terms in our sequence that are below the 8th term and above the eighth term: 6.

Statement 2 tells us that the eighth term in the sequence is 10, so there must be 6 terms in the sequence greater than 10.

Statement 2 alone is sufficient.

How did you do on the practice test? This seems like a pretty difficult question. :)
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by vaivish » Thu Oct 02, 2008 9:52 am
great dude...thanks but how did u solove.....i couldnt on the test........
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by gmatutor » Thu Oct 02, 2008 11:33 am
When you are sure you can find the answer with both A and B, the next question you can ask yourself is if you could have figured it out with one alone.

I think this helps because you don't always consider all the ways that you could find the answer with statement 1 alone and all the ways that you could find the answer with statement 2 alone.

However, once you know what the answer is you can sometimes see new ways of getting there. It is always easier to find your way to someplace the second time you go.

So in this case when I looked at both statements together it became clear that there must be exactly 6 terms in the sequence greater than 10. I asked myself how else could I get the answer 6 from the information given. Then I noticed there were exactly 6 terms above the 8th term and 6 terms below.

I wouldn't recommend people use this strategy until they have gotten very good at evaluating statement 1 and 2 alone without confusing the two.
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by Toph@GMAT_REBOOT » Thu Oct 02, 2008 11:45 am
I missed this problem when I took my GPrep 1 exam.

K is either going to be negative or positive. Since it's a constant, it will always be the same number.

Statement 1 does not give us the means to solve K.
Statement 2 does not either. But since, as gmatutor has pointed out, the term given in this statement is in the middle of our terms, it doesn't matter. Since K isn't zero, it has to give us a linear sequence. If K = 1, and term 8 = 10, then term 9 = 11, term 10 = 12, and so forth. Meanwhile, term 7 = 9, term 6 = 8, etc.

If K = -1, then term 9 = 9, term 10 = 8; term 7 = 11, term 6 = 12, etc.

Either way, we'll get 7 terms that are > 10.
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by vaivish » Thu Oct 02, 2008 7:08 pm
thanks gmatutor....excellent post
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