Weighted Average IF (sumproduct conditional)

Hi,

I need a formula that gives me the weighted average of some values if they fall within a certain week.

So I have Weeks 1 to 6.

In each week there are multiple deliveries of different weights with different ratings. I would a like a formula that tells me average rating (weighted average - presumably using a sumproduct formula) of each week.

The end result is a table with the week in column A and the weighted average rating of that week in column B.

I have attached the excel to illustrate the problem.

Any help would be great, and would be even better if you could put the formula into the excel and share so I can see it working!

Thanks,

Leo