OG - DS - #146

by **mrkamal** Tue Jul 31, 2007 11:40 am

Hi,
Having trouble with a problem, DS #146 from OG 11th Ed.
Q:
Is n an integer?
1) n^2 is an integer
2) square root of n is an integer
Answer: B

I'm just unclear as to why the answer is not D? It seems to be if n^2 is an integer, then n also has to be an integer, which would make statement 1 sufficient, no?
Thanks

by **Luci** Tue Jul 31, 2007 12:43 pm

Hi,

Statement (1): n^2 is an integer

If for example you do the SQR of 5 you get 2.236068

So 2.236068^2=5

Here you have an example in which n^2 is an integer but n it is not.
NOT SUFFICIENT

Statement (2): SQR of n is an integer

If the SQR of n is an integer, then n obviously has to be an integer
SUFFICIENT

Hope itÂ´s clear

by **Guest** Tue Jul 31, 2007 10:55 pm

Perfect, thank you!

by **dbernst** Thu Aug 02, 2007 11:32 am

Thanks, Luci!