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by Suyog » Tue Oct 09, 2007 3:10 pm
Is the integer n even ?

(1) n^2 - 1 is odd.
(2) root n is an integer.
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Source: — Data Sufficiency |
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by achandwa » Tue Oct 09, 2007 3:29 pm
Answer is A.
i) n^2-1 is odd
This tells you that n is even, because if it were odd, its square would be odd too (odd*odd=odd) and n^2-1 would be even.

Sufficient.

ii) Root of n is integer
This doesn't tell you if n is even. For example, Root of 9 is 3 (an integer), Root of 4 is 2 (an integer) as well.

Insufficient
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