Puzzle #1

[Empirical]

Imagine you are a contestant on a US game show. You have the chance to win a Rolls-Royce (or a Porsche).

There are three doors, and you must choose one. The Rolls is behind one of the doors; there are goats behind the other two.

You choose one door, let's call it A. but you don't open it. The host—let's call him Monty—chooses another, say B, and opens it; there is a goat there.

Now it's your turn to open a door. Monty asks if you want to stick with your original choice A, or if you want to change and open the third door, C.

So, should you go for A or C? And why?