Running Average of last n row if sum is between a certain value

[ttngu17]

Hi there,
I'm looking for a formula to show the running average when the sum of the last n rows "B" is between a certain value, for example 500 to 550

Running Average of Cost when the sum of previous # row in B is between 500 to 550.

A	B	Cost	Running Avg	Row included in running average
1	100	2000
2	100	2000
3	75	1500
4	75	1500
5	50	1000
6	50	1000
7	50	1000	1550	1-7
8	100	1000	1350	2-8
9	100	1000	1150	3-9
10	100	1000	1071	4-10
11	100	2000	1200	6-11
12	100	2000	1400	8-12

Thank you very much in advance!

 

[Peter_SSs]

I don't understand your examples. Based on the rows you have listed in that last column and assuming the relevant rows are the ones listed in the first column, I have entered average formulas below and they do not give the results that you have shown. What am I missing?

BTW, I suggest that you investigate XL2BB for providing sample data & expected results to make it easier for helpers to understand just what you have & where it is and also what you want & where it is to be.
(If you have trouble with XL2BB, review the "XL2BB Icons greyed out" link in the 'Known XL2BB issues' section near the top of the XL2BB Instructions page linked above.)

24 10 16.xlsm
	A	B	C	D	E
1	A	B	Cost	Running Avg	Row included in running average
2	1	100	2000
3	2	100	2000
4	3	75	1500
5	4	75	1500
6	5	50	1000
7	6	50	1000
8	7	50	1000	1428.571429	1-7
9	8	100	1000	1285.714286	2-8
10	9	100	1000	1142.857143	3-9
11	10	100	1000	1071.428571	4-10
12	11	100	2000	1166.666667	6-11
13	12	100	2000	1400	8-12
Running average

Cell Formulas
Range	Formula
D8:D11	D8	=AVERAGE(C2:C8)
D12	D12	=AVERAGE(C7:C12)
D13	D13	=AVERAGE(C9:C13)