horse racing riddle, page-48

Got it 7.

1. 5 races with all Horses.
2. Race the 5 winners.
3. Pull out the fastest horse from the winning race and replace it with the number 2 race in the same heat at was one by the eventual winner.

the then you can get 1 2 and 3 with certainty.

If the new horse that came second in the first race wins you will need an 8 th race adding in the 3 rd horse in the the final race after removing the winner in race 7.