Calculating current grade percentage

[lintonindy]

I'm sure this has been answered before, but I can't find it in the search

If I have values in column B (B3:B18) and enter in values in column C
(C3:C18) and want to find the current total percentage in cell C19 how do I
set up the formula to only add the cells in column B that have values in
Column C?

Example

A B C
Week 1 20 20
Week 2 20 20
Week 3 20 20
Week 4 20 0
Week 5 20 20
Week 6 20 20
Week 7 20 0
Week 8 20 20
Week 9 20 20
Week 10 20 20
Week 11 20 20
Week 12 20 0
Week 13 20 20
Week 14 20 20
Week 15 20
Week 16 20
Current % ?

Since 15 and 16 are "" I can't just add up column C and Divide by the sum of
column B. I also want to be able to adjust from just entering in one grade
Ex: C3

Thank you soooo much for the help

 

[David Biddulph]

=SUM(C3:C18)/SUMPRODUCT(--(C3:C18<>""),B3:B18)

 

[Tom Hutchins]

Try this in C19...

=SUM(C3:C18)/SUMPRODUCT(--(LEN(C3:C18)>0),(B3:B18))

Hope this helps,

Hutch

 

[lintonindy]

That helped a lot thank you very much and I tried to use what you gave me to
adjust another incorrect formula, but I'm not very good with this. Just one
more I promise. This is for the total % to multiply by in cell M22. Notice
that cell M19,M21 are blank and I don't want to add the % to the current
total poss. Answer is 70% out of 100%.


A B C D E F G H
I J K L M

Current sec % 78% 78% 100% 0%
95%
% of grade 25% 10% 5% 5%
25% 30%
%earned 19.6% 7.86% 5% 0%
23.75%
Total Current %
M22 ?
So I need to add (C20:M20) when there are values from (C19:M19) but only
when there are corresponding values. Answer with simple math is 70% about
the only thing I know how to do. Thanks again for the help.

 

[lintonindy]

Tom's formula worked great as I'm sure yours would also. If you could, look
at my reply to Tom for my other?. You guys are unbelievable, thanks for yur
help