I need some help writing an average function. This is what I have right now.

=SUM(Sheet2!$K1:$K25)/COUNTA(Sheet2!$K1:$K25)

I need to have the function validate two other columns.

Ex: if Column a = 2001 and Column b=Dec the aveage the values that corespond in column K.

Any Clue????

How i Tackled this is to use this Function

=SUMPRODUCT((Sheet2!A1:A25=2001)*(Sheet2!B1:B25="d ec")*(Sheet2!K1:K25))/SUMPRODUCT(((Sheet2!A1:A25=2001)*(Sheet2!B1:B25="d ec")))

the Numerator produces the sum of all the values in K1:K25 where your two conditions apply.

The Denominator counts all the cases where A1:A25 = 2001 and B1:B25 = "dec"

so the average is Sum/Count

Hope this Helps

David