is n an integer

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by Rahul@gurome » Sun Sep 05, 2010 10:16 pm
(1) If n = 1/2, then 2n is an integer, but n is not an integer in this case.
If n = 2, then 2n = 4, which is an integer, and n is also an integer here.
No unique answer.
(1) is NOT SUFFICIENT.

(2) If n = 1/3, then 3n is an integer, but n is not an integer in this case.
If n = 2, then 3n = 6, which is an integer, and n is also an integer here.
No unique answer.
(2) is NOT SUFFICIENT.

Combining (1) and (2), 2n and 3n are integers.
2n and 3n can be integers if n is a multiple of 6, so n will always be an integer.

The correct answer is [spoiler](C)[/spoiler].
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