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Riddle: 25 Horses Problem
posted by deep008 - September 05 2014 06:55:16 PM

Riddle: 25 Horses
You have 25 horses. When they
race, each horse runs at a
different, constant pace. A horse
will always run at the same pace
no matter how many times it races.
You want to figure out which are
your 3 fastest horses. You are
allowed to race at most 5 horses
against each other at a time. You
don't have a stopwatch so all you
can learn from each race is which
order the horses finish in.
What is the least number of races
you can conduct to figure out
which 3 horses are fastest?
Reply by deep008 - September 05 2014 06:55:38 PM

Reply by deep008 - September 05 2014 06:56:02 PM

Reply by deep008 - September 05 2014 06:56:22 PM
test%0d%0a

Reply by ilikeconan - October 10 2014 07:23:46 AM
I got 7...

Reply by Polar - April 25 2015 11:50:59 PM
I also came up with 7.

Exp. Below:
[hide]First Race all the horses in sets of 5. This is 5 races. Then take the winner from each and race them. (1 race) You now know your fastest horse. but unsure of 2 & 3 for sure. In order to get the next fastest horses you need to race the 2nd and 3rd place horses from the original group the fastest horse came from, the 2nd place horse from finals race, the 2nd place horse from the 2nd places original 5 race, and the third place horse of the final race. [/hide]