You are in a television show where the idea is to win a car
as a prize. there are tree doors and the game show host tells you that there is a car behind one of the doors and nothing behid the other two and asks you to pick one. you pick one but the game show host opens another one, showing nothing. He asks you if you want to stick or change your mind. What should you do?
if he opened an empty one and you have not opened yours yet 50/50% chance it has something in it
Of course you should change your mind and switch, because that way you have 2/3 chances of winning the car versus staying put, where your chances are 1/3. So, you are twice as likely to win the car if you switch.
You should switch.
Think of it this way...
There are 3 curtains, and only 1 has the car, correct?
That's a 1/3 chance.
HOWEVER, the host has showed you an empty curtain. Now there are 2 curtains left, only 1 with the car.
That means the probability of each is 1/2 now.
A 1/2 chance is higher than a 1/3 chance, so I'd recommend switching if you really want that car. 
Guest #6
True, you should switch, but your explanation isn't quite right. Watch this video of a Math Professor explaining the odds: https://www.youtube.com/watch?v=4Lb-6rxZxx0
