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by aroon7 » Sun Dec 28, 2008 10:40 am
the sequence will be:
1,-1,3,-3,5,-5....

sum of this sequence is positive when n is odd and 0 when n is even

(1) when n is odd, sum of the seq will be equal to n, which is positive. all the other numbers get cancelled
Suff.

(2)an is positive. this indicates that n is odd.
Suff

ans is D

Thanks!
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by vivek.kapoor83 » Sun Dec 28, 2008 10:53 am
my foolishness...it was damn easy...couldnt made the seq. ....wht hpnd to me...where my mind was wandering...i dont know...can u elborate 2nd stmt..im bit confused...wht it wants to say basically
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by cramya » Sun Dec 28, 2008 10:59 am
Sum of terms of AP = N/2 ( A1+AN)
N-> NUMBER OF TERMS
A1-> FIRST TERM
1N-> LAST TERM



Stmt I
n is odd

A1 and An are odd and both positive

suff

Stmt II

An is positive A1 is positive by whats geiven Ak = k if k is odd

SUFF

Choose D)
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by aroon7 » Sun Dec 28, 2008 11:00 am
vivek.kapoor83 wrote:my foolishness...it was damn easy...couldnt made the seq. ....wht hpnd to me...where my mind was wandering...i dont know...can u elborate 2nd stmt..im bit confused...wht it wants to say basically
cool down man...
don worry it happens.
take a chill pill and continue.

good luck!
B-)
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