Question 4 The investment return of a company in 4 years are given in the table below:. Year Return 2020 1851 2021 1874 2022 1854 2023 1867 (a) Using the single parameter exponential smoothing with a = 0.4, estimate the investment return in 2024. Show the steps clearly. t 1 Yt Ft (8 marks) 2 3 4 5 (b) Using the two-parameter exponential smoothing with a = 0.4 and y = 0.8, estimate the investment return in 2024. Show the steps clearly. (10 marks) t Yt Tt bt Ft 1 2 3 4 5 (c) Referring to (a) and (b), calculate the mean square error (MSE). (4 marks) (d) Referring to (c), which method of forecasting is better in this case - single parameter smoothing or two parameters smoothing? (1 mark) (e) In general, which method of forecasting is better - single parameter smoothing or two parameters smoothing? Justify your answer. (2 marks) [Total: 25 Marks]