Imagine you were on a game show and were told that behind one of three doors there was a new car and goats behind the other two. You are then allowed to select one door. The host then opens a second door and reveals a goat. The question is this: If given the option to switch would you do it?
Most people say no, figuring that there is a 50/50 chance that your original choice is right. Unfortunately, this is the wrong choice. By switching you have a 2/3rds — or 66.67% — chance of getting the car.
This is known as the “Monty Hall problem” and it vexes even mathematicians. To understand the counter-intuitive logic, I refer you to these two videos. The first is from the 2008 movie “21” and the second, and more detailed explanation, comes compliments of Ron Clark: