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Is x an integer?

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Is x an integer?

by Vincen » Wed Oct 11, 2017 6:38 pm
Is x an integer?

(1) x/3 is an integer
(2) 3x is an integer

The OA is A

Why statement (2) is not sufficient? And how can I prove, mathematically, that statement (1) is sufficient?
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Source: — Data Sufficiency |

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by Jay@ManhattanReview » Wed Oct 11, 2017 10:57 pm
Vincen wrote:Is x an integer?

(1) x/3 is an integer
(2) 3x is an integer

The OA is A

Why statement (2) is not sufficient? And how can I prove, mathematically, that statement (1) is sufficient?
Hi,

Statement 2 is not sufficient because @x = 1/3, 3x = 3*(1/3) = 1, an integer, so the answer is No; whereas @x = 1, 3x = 3*1 = 3, an integer, so the answer is Yes. No unique answer. Insufficient.

Hope this helps!

-Jay

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by Vincen » Mon Oct 16, 2017 6:57 am
Thanks Jay.

But, What about statement (1)?
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