I spent quite a lot of time trying to figure out this question that I read in a book. Through trial and error, I got a rough idea of what the solution should be like but can't figure out how I would derive it mathematically. Can anyone give me some directions? :) QUESTION: n people stand in a circle, where n > 2. we pick two person, A and B, at random. what is the probability that there are exactly r people standing in between A and B, in the clockwise direction?