Company ABC observes the demand of product X over 20 periods as follow: Period Demand Period (units) 68 75 1 2 3 456 7 8 9 10 Requirements: 72 84 87 86 93 96 99 105 11 12 13 14 15 16 17 18 19 20 Demand (units) 100 98 95 103 92 84 67 74 70 59 a) Plot a 10-periods Simple Moving Average (SMA) line against the actual data line over the 20 periods [Suggestion: Use MS Excel to plot the two lines and paste the chart onto MW Word] (5 marks) b) Compute the Mean Absolute Deviation (MAD) for periods 11 to 20. Tabulate your (5 marks) answers. c) Comment on the behaviors of the 10-periods moving average line against the actual data line. (5 marks) Note: Keep your answers to ONE (1) decimal place.