You have two buckets: one with only white marbles and one with only black marbles. The two buckets have the same number of marbles. How can you rearrange the marbles to maximize your chances of grabbing a white marble from each?
Put a single white marble in one bucket and put the rest of the white marbles and all of the black marbles in the other. This makes your odds about 75 percent for grabbing two white marbles.