Twenty-five horses, a track with five lanes, and no stopwatch: you only know who arrives before who within each race. The question is how many races do you need to be completely sure of who the three fastest are.
The twenty five horses
Riddle statement
You have 25 horses and a track with 5 lanes. Only 5 horses can compete in each race, and you do not have a stopwatch: you can only know the order of finish within each race.
What is the minimum number of races necessary to identify with certainty the three fastest horses?