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by pandesag » Wed Aug 06, 2008 7:14 pm
If c & d are integers is C even ?

1) C^2 -1 is odd
2) (C-3) (D+2) is odd

I thought answer is A
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Source: — Data Sufficiency |
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by parallel_chase » Wed Aug 06, 2008 7:31 pm
The answer should be D.

Statement I

c^2-1 odd

Therefore C has to be even, Hence Sufficient.

Statement II

(C-3)(D+2) odd

it means C-3 is odd & D+2 is odd
C-3 can only be odd if C is even.

Hence Sufficient.

Answer D.

Whats the OA?
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by pandesag » Thu Aug 07, 2008 7:30 pm
OA is D.
(C-3) (D+2) is odd.

This can be a possible scenario
even * Odd = Odd
Odd * even = odd

if C-3 is even C is odd
if C-3 is odd C is even

Can you please help in this inference that for (C-3) (D+2) to be odd
C-3 has to be Odd

Thanks
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by parallel_chase » Thu Aug 07, 2008 7:38 pm
pandesag wrote:
This can be a possible scenario
even * Odd = Odd
Odd * even = odd
These two scenarios can never be possible

even * Odd = Odd
4*5=20

Odd * even = odd
9*2=18

I think you are confusing this addition rule.
even + Odd = Odd
Odd + even = odd

Let me know if you still have any doubts.
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