OG 11 DS#99

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Junior | Next Rank: 30 Posts
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OG 11 DS#99

by [email protected] » Sat Jun 14, 2008 9:29 am
Is m NOT EQUAL TO n?


1) m+n<0
2) mn<0


My approach was

From Statement 1 : m<-n therefore yes sufficient

From Statement 2 : one of the numbers should be negative.Therefore sufficient

My answer was D

But OG says the answer is B.Please explain where i went wrong

Thanks
Peer

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by anshul265 » Sat Jun 14, 2008 10:15 am
i) m+n<0

1. m is -ve and n is +ve where -m>n
2. m is +ve and n is -ve where -n>m
3. m is -ve and n is -ve

In the 3rd case, m and n can be same. Eg -2. (-2)+ (-2)=-4 which is <0.

This condition is INSUFFICIENT.

Thus answer is B.

Junior | Next Rank: 30 Posts
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Thanks

by [email protected] » Sat Jun 14, 2008 11:35 am
Thanks

Although by subsitituition i could understand,your breakage into different categories helped me understand that we should consider both + ve & -ve values in inequalities

Peer