The horse puzzle

1. You have 81 horses
2. In a race not more than 9 horses can be made to run at the same time.
3. There is no timer to time the horses however u can rank the horses.
4 .How many minimum number of races have to be conducted to identify the best four horses.

--Asked by Koole Keshava

Solution

Divide 81 horses into 9 groups.....run each group pick the best one...so after 9 races u have best 9 horses.
Run the best 9 horses.....pick the best one among them,now pick the horses in 2,3,4 positions in the group from where best horse emerged.Now totally ten races over...best 1 is selected,
among the best 9 that we run eliminate horses in 7,8,9 positions and add those horses selected(2,3,4 positions).Run the 9 u ll get the best 4!!!
!!!RACE IS OVER!!!

--Cracked by Kavya