Average All Values Returned by Index?

Hi! I'm still pretty new at Excel, and I have a big set of data that is organized (among other ways) by day of the week. I'd like to get the average value for each day of the week (so, the average of all Mondays, the average of all Tuesdays, etc. etc.) I thought that something like this:

=AVERAGE(INDEX(B:C,MATCH("Monday",C:C,FALSE),1))

would do it (the data is in the column before the day of the week), repeated for each day, but this only returns the first value that the function finds. Is there a way to get all of the values, so it can be averaged?

Thanks, and please let me know if you need more information in order to help!

Cool, thanks! I changed it a bit, with further research (coz I have some days of the week without data yet) to be:

=SUMIF(C2:C113,"Monday",B2:B113)/SUMPRODUCT(--(B2:B10000>0),--(C2:C10000="Monday"))

But it works great. Thanks for your help.