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GMAT Prep1 - Hard Cons. Integers

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Source: — Data Sufficiency |
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by this_time_i_will » Sun Sep 26, 2010 10:33 am
I: the sequence runs as:
for n=1: 1
for n=3: 1,-1,3
for n=5: 1,-1,3,-4,5
etc..so we see the sum is always positive. sufficeint.


II: sine an is positive, this means n is odd, because an is negative for even n. this is same info as stament I above. so this stmt is also sufficient.
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