goal seeker or solver for forecasting vs. actuals

Hello. I do a forecast for 12 months of data. Sometimes the manager will set the forecast to a certain percentage. Let's say 13% for 2013 over 2012. However, when a month of actual data comes in, this will obviously shift the year % growth. Is there a way that I can modify each month equally to get to the original 13%? An example, January comes in over forecast and pushes forecast to 15%. For the remaining 11 months, I would like to apply a standard percentage decrease to get the overall yearly number back down to 13%. I hope this is possible. Thanks.

Do you really need “Goal Seek” or Solver?

You problem is (15 + X*11)/12 = 13 and reshuffling that by multiplying both sides with 12 and keeping X on the left side of the equation you get X =(13*12 -15)/11 i.e.

for the rest of year (11 months) the growth must be 12,818 % /month in order to get 13 % as the average.

Alf

Basic math over excel!!! I like it....