The following are monthly actual and forecast demand levels for May thur December for units of a products manufactured by the N. tamimi Pharmaceutical Company
Month Actual demand Forecast Demand sales
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.(show work)