Averaging using the date instead of day of the week

[coliervile]

On worksheet 1 I have 18 columns (A thru R). Column A has dates starting in Row 3 (A3) and runs down to 1095 in ascending order. In Columns I, L, and O (starting in Row 3 too)has numbers (changes in daily fund closing prices) that I want to average. I want to to average Columns I, L, and O by the days of the week (Monday thru Friday) on worksheet 2 (the headers on worksheet 2 starting in A1 are the day of the week name) by using the dates in Column A. Is this possible to do this with a formula? Also can the formula average (starting in Row 3) down until the last filled row when new rows are added?
Thanks,

Charlie

 

[coliervile]

That works FANTASTIC!!! Thank you so very much for you all of your thoughs and help with this. Have a great day.

Best regards,

Charlie