Hi puntz,
I'm not sure what you're on about - no doubt Mark will help, but since you're talking averages...
where an average is used in horse analysis calculations, most people calculate the arithmetical mean, as in your example above.

Often a more useful figure is the harmonic mean - calculated by the sum of the reciprocals (ie if number is x, the reciprocal is 1/x). This figure accounts for the frequency as well as the raw sum of the numbers.

I find there a many situations where this is more useful.

I have no idea whether this is of any use to you, but it may be of interest.