4b7. Can someone show me how to do this problem? steps with explanations please

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The following table shows the actual demand observed over the last 11 years: Year 1 2 3 4 5 6 7 8 9 10 11 Demand 6 10 4 9 12 9 12 12 8 11 7 This exercise contains only parts b, c, and d. b) Using the 3-year moving average, provide the forecast from periods 4 through 12 (round your responses to one decimal place). Year 4 5 6 7 8 9 10 11 12 Forecast c) Using the 3-year weighted moving average with weights 0.15, 0.30, and 0.55, using 0.55 for the most recent period, provide the forecast from periods 4 through 12 (round your responses to two decimal places). Year 4 5 6 7 8 9 10 11 12 Forecast d) Mean absolute deviation for the forecast developed using the 3-year moving average is 2.11 and for the 3-year weighted moving average is 2.39. Based on this information, the better forecast is achieved using the approach