here is a real puzzle

You have :

* 2 identical vases
* 3 white marbles
* 3 black marbles

You can distribute the marbles in the 2 identical vases in any way you wish.
After you place the marbles in the vases, the vases are shuffled without your looking.
You can now draw a single marble from only one vase (either vase)

Question: Which way should you have originally distributed the black and white marbles in the 2 vases to maximise your chances of your single draw being a *black* marble ?