n

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n

by fruti_yum » Sat Aug 01, 2009 8:11 pm
If n is a positive integer, what is the value of n ?
(1) When n is divided by 3, the remainder is 2.
(2) When n2 is divided by 3, the remainder is 1.


OA is C
I think it is E
Source: — Data Sufficiency |

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by navalpike » Sun Aug 02, 2009 6:53 pm
n>0

(1) When n is divided by 3, the remainder is 2.
Using the remainder equation –
N = 3(k) +2
Could be any number that is 2 greater than a multiple of 3. Insuff.

(2) When n2 is divided by 3, the remainder is 1.
N^2 = 3 (m) + 1
Again, same problem as 1. Could be multiple numbers. Insuff.

When we combine, we can substitute the value of n from S1 into S2
(3k+2)^2 = 3m+1
9k^2 + 12k + 4 = 3m + 1
3(3k^2 + 4k) = 3m – 3

We have multiples of 3 on both sides, thus the remainder will be 0. Suff.

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by adityanarula » Sun Aug 02, 2009 8:11 pm
I think it is E.

Try for n = 2 and n = 5

Stmtn 1: rem is 2 for both 2 & 5

Stmnt 2: rem is 1 for both 4 & 25

Thus, E