Formula development help

[mech contractor]

[TABLE="width: 500"]
<TBODY>[TR]
[TD]Total Lin Ft[/TD]
[TD]Wk-1[/TD]
[TD]Wk-2[/TD]
[TD]Wk-3[/TD]
[TD]Wk-4[/TD]
[TD]Wk-5[/TD]
[TD]Wk-6[/TD]
[TD]Production LF Over Under[/TD]
[/TR]
[TR]
[TD]300[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]400[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]200[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]1120[/TD]
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[TD][/TD]
[/TR]
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[/TR]
[TR]
[TD]I just can’t seem to develop a formula for this; any help would be much appreciated.
<o> </o>
I am trying to develop a production / installation tracking sheet given a total linear footage of material to be installed in 6 weeks.
<o> </o>
The formula will need to be based on installation footages, wk-1, then Wk-2 up to 6 weeks. Based on the average linear feet installed each week I need the productivity column to indicate given the averages each week what is the linear footage that will be either ahead or behind at 6 weeks
<o> </o>
Thanks much all
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</TBODY>[/TABLE]

 

[mech contractor]

I have been working on this for hours ...... thanks so much

 

[Mindpsyche]

No worries, glad it helped. By the way use this formula if your using mine.

Small fix:

=SUM($F5:OFFSET($F5,,COUNT($F5:$K5)-1))/COUNT($F5:$K5)*6-$D5