I have seen this question and has been intrigued by the various ways this question can be solved, I do know one, trying to find if there is any other approach possible, the acceptable answer has to provide a methodology, preferably multiple along with the answer to the question.

There are 25 horses and 5 tracks, horses run at their original sped regardless of how many races they run, what is the least number of races needed to determine the top 3 horses. There are no stop watches or other equipment and the only way to determine the order is ranking in a specific race.