A smiling 203 IA walks up to you, holding three cards.

The first is red on both sides, the second is red on one side and black on the other, the third is black on both sides.

Card 1

Card 2

Card 3

Now, he shuffles these three cards, and shows you one of the sides. If you see red, which color do you think is on the underside?

Surely, if you see red, then the other side is either red, or it's black. So it should be 50/50, right?

Let's run an experiment to find out. The buttons below run 1/10/1000 runs of this game and prints the probabilities in the table on the right

You saw:

Back of card:

Total # of Runs: 0

Front / Back Red Black
Red 0% 0%
Black 0% 0%