Wrong Solution for Fastest Horse Puzlle


#1

The complete solution for this problem is wrong. We have been asked to find out the fastest 3 horses out of 25 horses. Maximum of 5 horses can be raced together.
Now the answer given is 7 which is wrong because when we divide horses in groups of 5 and race them, we can’t assure that the winners of these races are the 5 fastest horses out of the 25, it just means that they were the fastest in their group.
In my opinion, solution should be 5 horses are raced, the last 2 horses are eliminated and next 2 horses are added, till there are no horses left. Now the top 3 horses of the last race are the fastest 3 horses.
Number of races required = 1(first 5) + 20/2(2 horses are added, 20 are remaining) = 11.


#2

Agreed. 7 is not the solution. Me too solved it with same approach and got 11.


#3

Found out another proper explanation for the answer 7. This sounds good to me.
http://puzzles.nigelcoldwell.co.uk/fiftynine.htm