Not sure how you want to calculate the average age but this will give you an
average birth year:

=SUMPRODUCT(A1:A5,B1:B5)/SUM(B1:B5)

Based on your sample data the average birth year is 1920.5

Now you get to decide how to round that off. Up or down?

--
Biff
Microsoft Excel MVP


"Roger" wrote in message
...
I created a spreadsheet with 2 different fields.
Birth Year Mbrs
1918 4
1919 5
1920 4
1921 6
1922 11
As we have 4 members born in 1918 and 5 mbrs in 1919 etc.
Thank you
--
Roger