In the English Championship division, there are 24 teams, 8 of which have names starting with the letter B (-e.g.Bolton). Tonight,(5th March 2013) all 24 teams in this division are playing each other. The 8 teams starting with B are playing each other, by a coincidence., i.e. 4 of the games involve these 8 teams ( there are 2 teams per game) What is the probability of this happening ? I'd really like to know how to work this out.