Last night seven of my friends went to a local restaurant. They each handed over their coat as they entered. At the end of the evening the staff returned the coats, but they were totally incompetent and randomly handed out the coats to my friends. What is the probability that exactly six of my friends received their own coat?
As ever, please do NOT post your answers, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.
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.