2016/074) you have 25 horses and you have to pick fastest 3 out of the 25. In each race only 5 horses can run at the same time as there are only 5 tracks. what is the minimum number of races to pick the 3 horses without using a stopwatch.

you make the horses into 5 groups of 5 horses each say A,B,C,D,E . have 5 races. then pick the winner of the 5 races and have
a race that is race number 6.. Now pick the 3
winners out of the 5. Say the winner is from group A, the 2nd ranked is from Group B and 3rd one is from group C.
now let the 1st 3 postions in group A be A2,A2,A3. in group B be B1,B2,B3. and in group C be C1,C2, C3.
A1 is the 1st. B3 cannot be in top 3 beacuse A1, B1, B2 are faster.
So B3 is ruled out.
C2 and C3 cannot be in top 3 as A1,B1,C1 are faster. So have a race among A2,A3,B1,B2,C1 and choose the 2 fastest. the ranks
shall be 2nd and 3rd.
So we need 7 races.