2 puzzles from Marilyn vos Savant, 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're shown three doors. Behind one is a car, behind the other two are goats. You pick a door, then the host, who knows what's behind each one, opens a different door to reveal a …
— Marilyn vos Savant, Ask Marilyn