Something like this should do the trick...
=IF(AND(WEEKDAY($A3)1, WEEKDAY($A3)<7), (SUMPRODUCT(--($A$3:$A$9=$A$11),
--($A$3:$A$9<=$A$12), B$3:B$9)+SUMPRODUCT(--($A$3:$A$9=$A$11),
--($A$3:$A$9<=$A$12), D$3:D$9))/5, "")

My source data looked like this
A B C D E F G
2 Date ProdA ProdB ProdA ProdB
3 4-Feb-08 30 10 20 10 61 37
4 5-Feb-08 10 15 10 15 61 37
5 6-Feb-08 50 15 25 10 61 37
6 7-Feb-08 20 10 20 20 61 37
7 8-Feb-08 10 10 30 20 61 37
8 9-Feb-08 10 15 40 15
9 10-Feb-08 20 10 10 10
10
11 4-Feb-08
12 10-Feb-08


--
HTH...

Jim Thomlinson


"Cam" wrote:

Hello,

I am not sure what formula to use to calculate the weekly average, which is
the range of the week data (Monday to Sunday). Example: date range from 2/4
to 2/10/08 week is the sum of data from 2/4 to 2/10 divided by 5 (weekday).
Below is a sample of data and results I want to achieve.

Data:
Type1 Type2 WeekAvg
Date ProdA ProdB ProdA ProdB ProdA ProdB
2/4/08 30 10 20 10 61 37
2/5/08 10 15 10 15 61 37
2/6/08 50 15 25 10 61 37
2/7/08 20 10 20 20 61 37
2/8/08 10 10 30 20 61 37
2/9/08 10 15 40 15
2/10/08 20 10 10 10

Result column: WeekAvg for ProdA = 61
(30+10+50+20+10+10+20+20+10+25+20+30+40+10) / 5

Result column: WeekAvg for ProdB = 37
(10+15+15+10+10+15+10+10+15+10+20+20+15+10) / 5

NOTE: 2/9 and 2/10 are weekend so does not need to show value.