Seek Advise to Combine the Formula Created without Helper Row

Dear All,

I created a file to calculate the cash flow for a project.
I manage to distribute the cash flow into required months with helper row.

However, i found out that in the event my total duration to distribute the cash flow is different for different item, i need to create a low of helper row.
As such, i would like to seek advise on how to combine those formula without helper row.

Thanks.

The Current Distribution is based on Decline Curve

1) I generate a smooth decline curve by using "1 - norm.dist" formula as per Cell J1:BE1
the Formula that i use is =ROUND(IF($E8>=J$6,(1-NORM.DIST(J$5,$F8/2,$F8/$H8,TRUE)),0),4)

2) Based on the curve created, i introduce the factors for each month (some sort like a trend line) at J2:BE2
the formula that i use is = =IFERROR((J$1/SUMIF($J$1:$BE$1,"<1"))*1,"")

3) Once i created the factors in Step 2, i will use the budget amount multiply with the factor to generate the figure for that particular month at J8:BE8

My problem now is due to the duration at F9 is different from F8, i can't use the same figure created at Step 2, i need to repeat Step 1 and Step 2 with new duration and time.

If i have 20 activities i need to create 40 helper rows.

Is there any way to combine the formula?

test.png

Dear FlameRetired,

Thanks for your advice and sorry for the late reply.

I try to adopt your formula into my working file as enclosed,i noticed that whenever my value at Column "F" is changed,
the figure return did not match to the manual calculation using helper column.

You can compare the value for Row 11 = Row 24, Row 12 is not equal to Row 25, Row 13 is not equal to Row 26.

Am i typing wrong the formula or i miss out something?

Please advise.

testing 1.png