You have 3 boxes. One of them contains a prize. You were allowed to pick just one of them.
You pick - and it's empty.
With 2 boxes left, you now have one box in your hand and another box in front of you. If given the chance to exchange your box with the box in front of you, would you do it? Why, and why not?
(The 'Google Riddles' are interview questions those who wish to get hired were asked).