either pigs or cows

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either pigs or cows

by sanju09 » Thu Mar 24, 2011 4:18 am
Of the 60 animals on a certain farm, 2/3 are either pigs or cows. How many of the animals are cows?

1. The farm has more than twice as many cows as it has pigs.

2. The farm has more than 12 pigs.



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by HSPA » Thu Mar 24, 2011 5:17 am
C for me

2/3 are pigs and cows = 40
C- cows, p - pigs
P(C u P) = P(C)+P(p)-P(CnP) = c+p

1. c>2p
2. p>12

So p =13, c= 27

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by Anurag@Gurome » Thu Mar 24, 2011 5:34 am
sanju09 wrote:Of the 60 animals on a certain farm, 2/3 are either pigs or cows. How many of the animals are cows?

1. The farm has more than twice as many cows as it has pigs.

2. The farm has more than 12 pigs.

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Let total animals = T
cows = C and Pigs = P
Then (2/3) of 60 = P + C or P + C = 40

(1) C > 2P, It is NOT SUFFICIENT as there can be many possibilities.

(2) P > 12, It is NOT SUFFICIENT as there can be many possibilities.

Combining (1) and (2), If P = 13, then C > 26, so that P + C = 40
If P = 13, C = 27, then P + C = 40 (this is the only possibility)
If P = 14, then C > 28, if C = 29, then P + C = 43, not possible.
There are 27 cows. Hence, SUFFICIENT.

The correct answer is C.
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