Month	Historic Demand	Forecasted demand	Forecasting error	mean absolute deviation
January	200
February	240
March	270
April	310	236.67	73.33	73.33
May	370	273.33	96.67	96..67
June	470	316.67	153.33	153.33
July	530	383.33	146.67	146.67
August	620	456.67	163.33	163.33
September	540	540	0	0
October	360	563.33	-203.33	203.33
November	320	506.67	-186.67	186.67
December	290	406.67	-116.97	116.67
		Total of errors	126.67	1,140

a. Use the three-month simple moving average to forecast sales for the months April through December. b. Based on the results of this exercise for the first five months of demand for these products, evaluate how effective the calculated forecast is.