> If Alice tosses a coin until she sees a head followed by a tail, and Bob tosses a coin until he sees two heads in a row, then on average, Alice will require four tosses while Bob will require six tosses (try this at home!), even though head-tail and head-head have an equal chance of appearing after two coin tosses.

Ok, I verified on 10 000 tosses, it works, but I cannot see why. Can somebody explain?

Edit: nevermind, it can be found in the previous discussion.