It’s the Friday Puzzle

First, as I mentioned yesterday, we have just released the Night School Sleep music on iTunes.  This 30 minute piece is scientifically designed to help you fall asleep and can be downloaded here.

Second, today I am off to New York City to see the premiere of a new documentary about James Randi.  I have seen a rough cut and it looks jolly good.  You can see the trailer here. If you get a chance to see it, go watch.

Finally, here’s 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.

Imagine a mythical family in which each daughter has the same number of brothers as she has sisters. In addition, each son has twice as many sisters as he has brothers. How many sons and daughters are there in this mythical family..?

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.