=if(Grades!D2=1,Sumproduct(Weights!$A$2:$C$2,Grade s!A2:C2),Sumproduct(Weight
s!$A$3:$C$3,Grades!A2:C2))

--
Regards,
Tom Ogilvy

"David" wrote in message
...
Hello,

I am trying to write a function to calculate an average.

I have a range from which I choose a formula:

math english sport formula
30% 30% 40% 1
20% 40% 40% 2

and another range with grades:

math english sport formula total_grade
50 60 80 1
60 80 90 2

How can I write a function which will calculate total grade upon formula
value
(use formula according to the value in the second range) ?

Thank you
David D.