4) A small manufacturing firm has recorded a time series of the cost per unit for the firm's leading product over the past eight years. Year 1 2 3 4 | 5 | 6 7 8 Cost/Unit ($) 20 24.5 28.2 27.5 26.6 30 31 36 a) If you are not given a base value or trend, what would be the forecast for the year 10 made at the end of year 8 (a=0.2, =0.4). b) Forecast for the year 9 using 1) 5-month weighted average using 0.1,0.1,0.1,0.2,0.3, with the heaviest weight applied to the recent month 2) Exponential smoothing using a =0.2 and forecast of 21 for year 5 3) If a value was not provided in the question above, what value of a would you choose?