I have a user that wants me to calculate the average of a quantity for 16 days, then re-average that quantity for the whole month on the assumption that the quantity for the remaining days is equal to the average.

Now I think that the final result will be the same as the first average, & I’m going through a lot of pain for nothing.

After all:

n(avg(x[sub]1[/sub],…x[sub]n[/sub]) = x[sub]1[/sub] + x[sub]2[/sub] + … + x[sub]n[/sub]

therefore

(n+y)(avg(x[sub]1[/sub],…x[sub]n[/sub]) = x[sub]1[/sub] + x[sub]2[/sub] + … + x[sub]n[/sub] + y(avg(x[sub]1[/sub],…x[sub]n[/sub])

right?

Can you think of an easier way to express this?