Here’s the situation
You are shown three doors (by me). You are told that a prize is behind on of the doors, and a booby prize is behind another. You are asked to choose a door.
You choose a door, and I leave it closed. I then open another door, which contains the booby prize.
You are then asked if you want to change your mind, and switch doors to the one I didn’t open.
Do you switch or not?