Farmer Joe owns a cow, a goat, and a sheep. The animals each eat grass at a constant rate, and the grass grows at a constant rate. And Farmer Joe occasionally lets them eat the grass on a small pasture of his.

• If the cow and the goat graze together, the pasture is bare after 45 days.
• If the cow and the sheep graze together, the pasture is bare after 60 days.
• If the cow grazes alone, the pasture is bare after 90 days.
• If the goat and the sheep graze together, the pasture is bare after 90 days, also.

How long will it take for the pasture to be bare if all three animals graze together?

Lets divide the pasture in 2 halves.

The cow takes 90 days to finish off the whole pasture...so it will take it 45 days to finish off half the pasture

Likewise, the Goat and Sheep together take 90 days to finish off the whole pasture...so it will take them 45 days as well to finish off the other half of the pasture

So in all it will take them 45 days

The first 2 statements are not required in this method...unless of course, i am way off the pasture... sorry track !!!

Posted by Syzygy on 2004-10-12 12:17:36