#### collegeitdept

##### Board Regular

- Joined
- Nov 14, 2008

- Messages
- 185

I have data table with sales numbers by product, its wheel base, and over platform for months ranging from Aug 2013 - Nov 2013. This data table will populate with the complete month sales numbers after the month has finished going forward.

I have a table to the right of the listing the sum totals for each product (by wheel base and platform) by each quarter (rolling).

Now I need help building a sumproduct average to calculate the quarterly average. This is not that simple because not all products (platform/wheel base) were available the entire quarter.

Also PLATFORM 3 in the tables are grouped - instead of listing platform 3a and platform 3b - using this in the formula: (LEFT($D$2:$D$100,LEN($J9))=$J9)

Because not all products were available for the entire quarter - and the formula will need to count how many months that product, platform, wheel base was available during that quarter I'm guessing "=MOD(MONTH(A1)-1,3)+1" this may have to be used to count the number of months into the quarter the product was available.

Please help by downloading the attached file.

https://dl.dropboxusercontent.com/u/15717201/Excel Question - quarterly average.xlsx

Thanks!