[im3w1l]

>What is a problem geometric mean solve?

I have stock position which changed in value by a factor of 1.10 2007, by a factor of 0.80 2008 by a factor of 1.15 2009. Is there any sort of representative number x for how much the value changed per year? The final value of my stock position should come out the same when using x for every year, i.e. x * x * x = 1.10 * 0.80 * 1.15