Hi,

I am trying to compute the weighted average of a data set, conditional
on two criteria. I know how to do it for one, but am struggling to
trigger the second. Any help would be appreciated. A simplified data
set is:

A B C
1 Year Size Return
2 1983 100 20%
3 1983 75 10%
4 1984 200 22.5%
5 1984 150 15%
6 1985 300 10%

I would like to be able to create a formula that would allow me to
calculate the weighted average of each year's returns if the size is
greater than 100.