You are travelling to point B from point A at a speed of 30mph. You travel back to point A from Point B (taking the same route) at 60mph. What is your average speed?

(In reply to Harmonic Mean by Richard)

Another physical context would be resistors that are connected in parallel. Their "average" resistance (not the equivalent resistence, of course) is the harmonic mean of the individual resistances.

Posted by JLo on 2006-10-31 12:45:56