Why do Buses Come in Threes?

"I should perhaps say that I know Rob Eastaway quite well, through his Maths Inspiration shows for teenagers, which are held in major city-centre theatres all over the UK. And I greatly value being a member of that team, not least because it is the only opportunity I get to play the electric guitar in public! But I wanted to include a fairly modern and wide-ranging popular maths book, and this one is, I believe, exceptional in the amusing and cartoon-illustrated way in which it relates mathematics to everyday life, with topics like ‘How fast should you run in the rain?’, ‘Which snooker shot is hardest?’ and even ‘Why do clever people get things wrong?’."