Demand data for a certain raw material in a workshop is given as follows: 2 3 4 6 7 8 Periods 1 Demand 62 126 81 44 120 76 42 5 58 (a) Using Microsoft Excel, plot the demand data. (b) Among the simple, double, and triple exponential smoothing methods which one would you choose to forecast demand in the coming periods? Why? (c) Based on the method which you suggest in part (b), forecast the demand during periods 11 and 12 (make all necessary initializations and choose 0.10 as the value of each smoothing constant whenever you need them). (d) Suppose that actual demand during period 9 turned out to be 58 units, how would you revise your forecasts for periods 11 and 12?