5. A retail company uses trend- and seasonality-corrected exponential smoothing to forecast seasonal demand. According to historical sales data, they find that Lo=1000 and To-20 at the end of 2020. Besides, their predicted seasonal factors at that time are 0.8, 1.4, 1.1, 0.9 for spring, summer, fall and winter, respectively. a) Help them forecast 2021 total demand at the end of 2020. (4 points) b) Suppose =0.2, B=0.5, y=0.5. Help them update the forecast of demand after observing actual seasonal demand successively (Fill in all blank cells in the following table). (16points) Season Actual Seasonal Level Trend Forecast demand factor 2020 Winter 1000 20 2021 Spring 800 0.8 2021 Summer 1414 1.4 2021 Fall 1133 1.1 2021 Winter 990 0.9 2022 Spring 2022 Summer 2022 Fall 2022 Winter 5. A retail company uses trend- and seasonality-corrected exponential smoothing to forecast seasonal demand. According to historical sales data, they find that Lo=1000 and To-20 at the end of 2020. Besides, their predicted seasonal factors at that time are 0.8, 1.4, 1.1, 0.9 for spring, summer, fall and winter, respectively. a) Help them forecast 2021 total demand at the end of 2020. (4 points) b) Suppose =0.2, B=0.5, y=0.5. Help them update the forecast of demand after observing actual seasonal demand successively (Fill in all blank cells in the following table). (16points) Season Actual Seasonal Level Trend Forecast demand factor 2020 Winter 1000 20 2021 Spring 800 0.8 2021 Summer 1414 1.4 2021 Fall 1133 1.1 2021 Winter 990 0.9 2022 Spring 2022 Summer 2022 Fall 2022 Winter