creating a running average

[Jay]

I have created a spreadsheet that creates an ongoing average for that week.
Each week the spreadsheet is saved and a new one is started. Instead of a
weekly average I would like to have an ongoing 5 day average for the current
sheet and saved sheets. How would I do this?

 

[Jay]

P.S. Each spreadsheet has five worksheets. One for each day of the week.