What percentage of the earth's water is contained within a cow?

Question

This question has supposedly been asked in Cambridge Uni interviews. I was just wondering if someone could come up with an answer...

Answer 1

Apart from sweat, I would say most of the water in a cow is contained on the inside... I'd say 99.9% of it was inside and maybe 0.1% was on its surface. :)

Answer 2

The earths total volume of water is estimated by Wikipedia at:
1,360,000,000 km3 , i.e. 1.36 x 10^9 km3
convert to cubic meters: 1.36 x 10^18 m3

A cow is about 1 x 1 x1 meter, or 1 m3

So we have 1/ (1.36 x 10 ^18) = .73 x 10 ^-18

or about 10^ -17 percent.