This is purely for interest, but so far Googling has come up empty.
Given the following dataset of the number of items bought in a fictional shop, is there a way of calculating the figure in yellow by only using the figures in pink?
I know taking the average of the figures in pink will give me the wrong result(in this case 3.22), but was wondering whether there's a mathematical way of doing this. I have tried searching for the answer, but can't seem to find anything. Maybe it's just me...