3. (30 points) A&B company is preparing its production plan for 2021. The quarterly demands of 2020 are given as follows: Quarter 1 2 3 4 Demand 200 190 250 290 Seasonality index for each of the quarter are 0.92, 0.90, 0.97, and 1.10, which are estimated based on actual demands from 2000 to 2020 and believe to be applicable to 2021. (1) Please apply Holter's method with a = B = 0.2 to forecast the demand of 2021 quarter 1. (15 points) (2) Continue to obtain the demands of all 4 quarters in 2021 (Use the idea of "multi-period forecasting". Don't need to update the seasonality index). (15 points) [Hint: For Holts method, L and T can be assumed as D and the linear slope between D and D4, respectively]