The following are monthly actual and forecast demand levels for May thru December for units of a product manufactured by the N. Tamimi Pharmaceutical Company:
Month Actual Demand Forecast Demand
May 100 100
June 104 120
July 104 100
August 121 115
September 104 105
October 115 110
November 109 120
December 120 125
Compute a tracking signal and determine whether the forecasts are in control.