Transcript (en)

Suppose you're on a game show and you are given a chance to choose from three different doors, all right? Now, behind one of the doors is a new car. Behind the other two, goats. Which door would you choose, Ben? Uh, door number one. Door number one. Ben chooses door number one. All right, now, the game show host, who, by the way, knows what's behind all the other doors, decides to open another door. Let's say he chooses door number three, behind which sits a goat. Now, Ben, the game show host comes up to you and says, Ben, do you want to stay with door number one or go with door number two? Now, is it in your interest to switch your choice? Yeah. Well, wait. Remember, the host knows where the car is, so how do you know he's not playing a trick on you trying to use reverse psychology to get you to pick a goat? Well, I wouldn't really care. I mean, my answer's based on statistics, based on variable change. Variable change? or he just asked you a simple question. Yeah, but you changed everything. Enlighten us. Well, when I was originally asked to choose a door, I had a 33.3% chance of choosing right. But after he opens one of the doors and then re-offers me the choice, it's now 66.7% if I choose to switch. So, yeah, I'll take door number two and thank you for the extra 33.3%. Exactly. People remember, if you don't know which door to open, always account for variable change. Now, see, most people wouldn't take the switch out of paranoia, fear, emotions. But Mr. Campbell kept emotions aside and let simple math get his ass into a brand new car. Which is better than that goat you've been driving around campus. All right, everybody. That's the end of the day. Thank you very much. Your graded papers are down here at the end. You can pick them up on your way out.