iNTELLIGENCE

IQ solution to: Playing cards in Las Vegas ♠

You may think as follow: “The back side has to be either red or white, that sounds fair, the probability is 50 %.”

But this is wrong.

As mentioned, we have three different cards. But the fact that one visible side is white does not mean that both possibilities do have the same probability. There are overall three white card sides: one has a red back side, and both others are the front and the back of the same card; i.e. white-red, white1-white2, and white2-white1. The conclusion is that the probability for a white back side is 2:3 or 66,67 %, and not 50:50. If you play enough games against the banker, he will bleed you white for sure.

Gimme more intelligence!