Bertrand's Box Paradox
You reach into one of three boxes and pull out a gold coin. The chance the other coin in that box is gold is not one half.
188910 min read
French mathematics
Joseph Bertrand
1822 – 1900
Professor at the École Polytechnique and the Collège de France, and permanent secretary of the Académie des Sciences. He is remembered for Bertrand's postulate on prime numbers, for the Bertrand model of price competition in economics, and for two quite different paradoxes in his 1889 "Calcul des probabilités" — the box paradox, and the random-chord paradox that showed "at random" is not a well-defined instruction.