Hello

Would anyone know how exactly I would create a formula to return a rolling 12 week average from data on my sheet?

row 1 contains a formula to return todays date
row 2 contains the day of the week e.g. Mon, Tue, Wed and so on
row 3 contains the date for that day from 1/1/14 to 31/12/14
row 4 contains data set 1 in this case hours claimed by staff for cleaning hours worked
row 5 contains data set 2 in this case hours planned for by the company for cleaning hours needed that same day.
row 6 shows the percentage efficiency of row 3 against row 4.

I want to create a formula that recognises the date in row 1 to look up the previous 12 weeks / 84 days results as in row 6 returning an average

Secondly I would like to create a formula that looks up the same data by day of the week so I can analyse any trends for poor efficiency on Mondays for example or super efficient Fridays as everyone wants to get home early!