First, this week I started a new channel containing life changing ideas in less than a minute. It is called In59seconds, and I hope that you will come over and take a look.
Second, here is the puzzle. Please do NOT post your answer, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.
A box contains two coins. One is a double-headed coin, and the other is an ordinary coin ( heads on one side, and tails on the other). You take one of the coins out of the box and look at one of the sides. It’s a head. What’s the probability that the other side also contains a head?
I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.