Average number of days overdue, between date ranges

Hi, I wonder if someone can help advise how to go about this

I have two worksheets a details and a summary. The details worksheet consists of three columns, A = target date, B = actual date and C = days overdue
What I want is to show the average number of days overdue for a specific month on the summary worksheet.

On the summary worksheet I have a column per month and then three rows, row 2 = Target Date, 3 = Actual Date and 4 = Days Overdue to show how many target dates were set during a month, how many actual dates were set and the average number of days overdue for the actual dates within each month.

I'm having difficulty with the days overdue row as there are a few variables, it needs to take the average number of days from Column C only if the actual date (column B) is within the specified month/date range.

Anyone have any suggestions for how to do this, or kind enough to draft up a formula for me

Many Thanks

Originally Posted by JBeaucaire

The AVERAGEIFS() function should make this simple:

=AVERAGEIFS(C:C, A:A, ">=2/1/2013", A:A, "<3/1/2013")

That's great, worked a treat. Many thanks for your help!