Please explain exactly what your are trying to average and what you want your weights to be. 3.2 is not the average of either column of your table. How did you get that figure?I have a data set and am making vertical profiles (depth on y axis)

I am averaging freshwater fractions for different water layers. Instead of doing a straight average, I need a weighted one in relation to the depth intervals.

For example:

Depth fAltantic

0 1

25 2

50 3

75 4

125 6

If I take a straight average it is 3.2. But it should be 3.5 (assume a linear relationship and add a point of (100,5) My data is not this "perfect" what equation can I apply to obtain averages over depths?