Month Demand Forecast 1 20 2 18 3 21 4 25 20 5 24 6 27 7 22 8 30 9 23 10 20 11 29 12 22 Maverick Jeans' demand manager decided to evaluate exponential smoothing to maintain comparability she used data from problem 6 (above). a. Use a starting forecast of 20 for month 4 to develop forecasts for months 5-12 and the first month of the next year. Use smoothing constants (?) of 0.2, 0.5, 0.8. calculate the average forecast error and mean absolute error.