Forecast a value

[arizona_0012345]

Hello,
I am trying to project future values.
For instance, PROJECT123 has the following spend. The trend of each project is the following: it starts off slowly, eventually, it reaches a peak, then it slows down. The graph should resemble somewhat of a normal distribution curve.
Month Spend
Jan 60 dollars
Feb 70 dollars
April 80 dollars
May 90 dollars
June 150 dollars
July 180 dollars
August 140 dollars
Sept ??

Based on the information given, what formula would I use to forecast Sept spend? If in the example above, the data stops at June and I am to forecast July's spend, will I use the same formula as in forecasting the Sept spend?

Any help is greatly appreciated.
Jamie

 

[Denis]

Based on the information given, what formula would I use to forecast Sept spend?

Were you not given a formula in class?

 

[arizona_0012345]

no formula