⅔think in odds.
THE DAILY PROBABILITY PUZZLEOctober 31, 2026 · ET
No. 038Bayesian reasoningMedium6 min

Which coin did you pick?

You choose coin A or coin B with equal chances. Coin A lands heads with chance 1/10; coin B lands heads with chance 9/10.

You flip that same coin three times and get two heads and one tail, in any order. Given those results, what is the chance you chose coin A?

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