How do I project yearly growth rates in Excel?

[Guest]

I'm trying to find a formula (ideally) in Excel that will allow me to take a
constant weekly sales growth rate (based on 2006 actuals), and apply it to
the current week's actual sales amount...resulting in a 2007 year-end sales
estimate. Is there a way to do this (plug-in, etc) WITHOUT having to
manually create a separate tab to calculate, then sum, each projected week's
actual?

 

[joeu2004]

I'm trying to find a formula (ideally) in Excel that will allow me to take a
constant weekly sales growth rate (based on 2006 actuals), and apply it to
the current week's actual sales amount...resulting in a 2007 year-end sales
estimate.

Giving you want I think you asked for:

=sum(C1:C8) + fv(A1, 52 - 8, 0, -C8)

where C1:C8 are the actual weekly sales amounts for the first 8 weeks
of 2007, and A1 is the average weekly sales growth rate based on 2006
actuals.

That is certainly not the way that I would estimate year-end sales.
So perhaps I misunderstand you. If so, please clarify your question.

 

[Guest]

Thanks, Joe...And yes--I realize there are much more sophisticated ways of
projecting sales, but I'm actually doing this for a friend who claims that
this over-simplified way of projecting sales is, in fact, what he's being
asked to do...at this stage.

In fact, he's being GIVEN last year's weekly average sales increase (0.40
%), and asked to apply it to the current year's sales totals to extrapolate
the remaining 42 weeks of 2007 (cell A1, in your example).

Thanks again for the help!