Brain Teasers · Twenty-Five Horses
25 Horses 5 Tracks Puzzle - Why It Takes 7 Races
25 horses, a five-lane track and no stopwatch: find the fastest three in as few races as possible.
What is the 25 horses puzzle?
It is a ranking puzzle with limited information. Each race orders five horses but gives no times, so the only facts you collect are of the form 'this horse beat that one'.
The skill it tests is elimination: you never need the full order of 25 horses, only enough comparisons to rule out every horse that cannot be in the top three.
How it works
Twenty-five horses, a track that takes five at a time, and no stopwatch. The story runs the five heats and the race of group winners, then asks for the minimum number of races to find the fastest three. You type your answer and check it. Then you step through the answer and the breakdown.
How scoring works
This teaser checks your answer. Any correct form counts - a fraction, a decimal rounded correctly, a percent, or the number in words. You get two tries before the answer opens. A correct first try earns a ticket; a second try or opening the answer early is recorded but earns nothing. The story teasers share one lifetime unlock for free users.
The key insight
After five heats and a race of winners (A1 > B1 > C1 > D1 > E1), cross out every horse with three known horses ahead of it. Only A2, A3, B1, B2 and C1 can still be 2nd or 3rd, so one more race settles it: 7 in total.
The full step-by-step solution lives at /brain-teasers/twenty-five-horses/solution.
A worked example
Heats rank each group. Race 6 puts A1 first overall. Groups D and E are out, C2 and below are out, B3 and below are out, A4 and A5 are out. Race 7 runs A2, A3, B1, B2, C1, and its top two finish 2nd and 3rd overall.
Common mistakes
• Answering 6 - after race 6, A2 and B1 have never met, so 2nd place is still open.
• Answering 8 or more by re-racing horses that were already ruled out.
• Forgetting that B2 can still be 3rd, behind A1 and B1.
Why interviews test this
Interviewers want the elimination argument and the reason six races cannot be enough. The written solution is at /brain-teasers/twenty-five-horses/solution.
Play Twenty-Five Horses on Outcry
Twenty-Five Horses is free to play on Outcry, in the Brain Teasers section, and every run is timed and scored. Read the guide once, then play Twenty-Five Horses and check your score against the strategy above. The guide book has a written guide for every other game, and the practice hub and mock assessments put the same skills under a real screen's clock.