Hi All,

I have a spreadsheet with a products list in the first column, then sales on each day going across.

Product Case Size Units Per Sale Sales Per Case Sunday 30/08/15 Monday 31/08/15 Tuesday 01/09/15 Wednesday 02/09/15 Thursday 03/09/15 Friday 04/09/15 Saturday 05/09/15
Product 001 30 5 6 6 2 7 3 3 3 9
Product 002 30 5 6 2 3 3 6 7 8 3

Those dates continue across for the full year as headers. Each day will have the products sales recorded. Then on a separate sheet I'm allowing the user to find a product (at the minute from a drop down box in B2), then have its information listed, along with the average sales for each day.

I can find the sales from the 1st week by searching for the product and the corresponding day. i.e
=INDEX(Table3,MATCH(Sheet4!$B$2,Table3[PRODUCT],0),MATCH("Sunday"&"*",Table3[#Headers],0))
but I don't know how to fit them into an array to calculate the average for all Sundays or all Mondays etc or calculate the average for the last 4 Sundays entered.

I tried 
'=AVERAGE(IF(Table3[PRODUCT]=Sheet4!$B$2,IF(Table3[#Headers]="Sunday"&"*",)))
but I don't know where to tell it to look for the result as the criteria gives the placement, like in my first formula.

Any help would be appreciated. It's going to be 365 columns of dates and around 100-200 products, so getting this automated and not hard coded would be great for expansion.