The other way to see it is by just looking at the different outcomes of car behind door A, B or C. Let's call the door you initially pick A. car initial monty

The other way to see it is by just looking at the different outcomes of car behind door A, B or C. Let's call the door you initially pick A. car initial monty stick swap A A B A C -- or Monty picks C, and you swap to B B A C A B C A B A C So, if you stick, get it right 1/3, but swap get it right 2/3.