Hum, I am not sure. I think the mean is correct as you stated, yet not sure about the median, as if it’s symmetrical then I would suspect that C is the mean, mode, and median, right? If not assuming C is the mid point then the mean is not the same as the median or mode.
Sorry about the latex markup. It does make the formulas difficult to read.
I’ve updated the formulas on Medium to images so a bit easier to view. You’ll find the updated article at https://medium.com/p/1dec93a263b6/edit
and you can find the original and other similar articles at…