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Source: — Data Sufficiency |
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by eaakbari » Sun Apr 18, 2010 3:50 am
IMO C

(1)

c(d+1)= even
There are 2 possibilities
- c = even and d = even or odd
- c = odd and d = odd

Insuff


(2)

(c+2)(d+2) = even
There are 2 possibilities
- c = even and d = even or odd
- d = even and c =even or odd
Insuff

(combined)

Charting our common possibility

c = even and d = even or odd

which tells us c is even

Hence C
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by kstv » Sun Apr 18, 2010 7:46 am
sandranjeim wrote:If c and d are integers, is c even?
1) c(d+1) is even
2) (c+2) (d+4) is even
C
2)(c+2) (d+4) = cd + 4c + 2d + 8 is even
so cd is even like the other 3 terms
Insuff
1) c(d+1) is even
cd + c is even
Insuff
but from 2
cd is even and cd + c is even
so c cannot be odd
IMO C
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