Downside Deviation

Having trouble with question 12A in SS 13 (Alternatives). How does the ciriculum arrive at the 28.78 that is in the numerator of the formula? I thought Downside Deviation = [Sum( Min(ARi - RRi , 0))^2 / (n-1)]^0.5

I guess 28.78 is suppposed to be this part = Sum( Min(ARi - RRi , 0))^2

But this is not what I am getting… Is this correct?

(-2.4167)^2*2 + (-1.4167^2)*2 + (-3.6167)^2 = 28.77547

look at the footnote - hurdle rate - 5% per year = 0.4167% per month.

Ah. I was squaring the sum instead of taking the sum of the squares. Got it. Thank you very much.

Btw, do you know of a good way to calculate sum of the squares using an HP12c? Perhaps it can be done using lists…