SumProduct over sets of cells (not contiguous)

Question

I have a total data set that is for 4 different groupings. One of the values is the average time, the other is count. For the Total I have to multiply these and then divid

Answer 1

Note that sumproduct(a, b) = sumproduct(a1, b1) + sumproduct(a2, b2) where range a is split into ranges a1 and a2 (and similar for b)