2 puzzles from Steve Selvin, each explained in a minute and credited to the original work. Free on Savvy.
A car is behind one of three doors; goats behind the other two. You pick door 1. The host — who knows where the car is — opens door 3, revealing a goat, and offers you the chance t…
— Steve Selvin; Marilyn vos Savant, A Problem in Probability (letter); popularised in Parade's 'Ask Marilyn'
You pick one of three doors, behind one of which is a car. The host, who knows what's behind every door, opens one of the other two doors to reveal it's empty, then offers you the …
— Steve Selvin (1975 letters to The American Statistician); popularized by Marilyn vos Savant, A problem in probability