On a certain pasture grass grows at a even rate. It is known that 40 cows can graze on it for 40 days before the grass is exhausted, but 30 cows can graze there as long as 60 days.

How many days would pasture last if 20 cows were to graze on it ?

(In reply to

Puzzle Solution by K Sengupta)

In the previous comment, we note that r = 10c

In other words, the daily growth of grass in the pasture is equal to the daily ration of 10 cows.

Thus, if 10 cows grazed in the pasture, the amount of grass at the start of any given day would always be equal to the initial amount.

Consequently, the pasture would support a *maximum* of 10 cows for an indefinite period.

*Edited on ***March 29, 2008, 9:27 am**