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DS Princeton Review Bin 3 Q9

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DS Princeton Review Bin 3 Q9

by givemeanid » Wed Jun 27, 2007 6:44 pm
If P is a set of integers and 3 is in P, is every positive multiple of 3 in P?

(1) For any integer in P, the sum of 3 and that integer is also in P
(2) For any integer in P, that integer minus 3 is also in P
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Source: — Data Sufficiency |
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by Jhyphi » Wed Jun 27, 2007 10:17 pm
I'm going with A.
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by discreet » Thu Jun 28, 2007 1:26 am
Yes,appears to be A.Here's my explanation:

Its given that 3 is in P,

(1) =>
3+3,3+6,3+9,....are all in P.If an integer is in P,then 3+that integer is also in P.So,it has to be an infinite set to satisfy this condition.To conclude,all positive multiples of 3 must be in P.

(2)=>

Using this we can conclude that All negative mutliples of 3 are in P but we cannot say that all positive multiples of 3 are in P.

any other views???
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by givemeanid » Thu Jun 28, 2007 6:47 am
The OA is (A).
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by aninditasivaram2406 » Mon Nov 12, 2007 11:31 pm
Option 2 will not be the correct answer. This is because if the number 3 is in the set, then 3-0=0 is also in the set. Ans 0 is not a multiple of 3...hope this sounds logical
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