Sizu Home › Calculators › Three Doors Game
Enter your numbers, then press Calculate.
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From the book, Chapter 8. With a host who knows and always opens a goat door, switching wins 66.7%; with 100 doors and 98 opened, 99%. With four doors and one opened, switching (to one of the two left) wins 37.5%. A host who opens a door at random and happens to show a goat leaves it at 50%. Over 30 games, always switching wins at least 15 with chance 98.1%.
The theory is exact; the game uses your browser’s random numbers. Rounds where a guessing host reveals the car are set aside, as in the book. Everything stays in your browser: no sign-up, nothing stored or sent.