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Calculate the three-month-weighted-moving-average monthly forecasts for the period April 2021 December 2021. Use weights of 0.5, and 0.2 for the most recent and oldest monthly data respectively and 0.3 for the middle month (show all workings). . .(9 marks) 4.2 Determine the Mean Absolute Deviation (MAD) of the three-month-weighted-moving-average monthly forecasts for the April - December 2021 period. (4 marks) a. The linear regression equation of the sales of reading glasses for the 2021 financial year is given by the expression: y = 201.4x + 4091 (where 'y' denotes monthly sales, and 'x', the number representing the month. For example, x = 1, 2, 3, etc., if the month is January, February, March, etc.). Use the regression equation to determine the Mean Absolute Deviation (MAD) of the regression forecasts for the April - December 2021 period. .(5 marks)

b. Which of the two methods is better at forecasting the sales of the reading classes? Explain. (2 marks)

Study the scenario provided below and answer all questions that follow. InSight Limited imports reading glasses from China for sale in a Southern African country. During the 2021 financial year, the company adhered to the policy of importing 6000 pairs of read ing glasses every month. The actual monthly sales of reading glasses by InSight Limited during the 2021 financial year is depicted in Table 2.1 below. The company paid R5 000 to place an order for the reading glasses and a carrying cost of R2.00 for each pair of reading glasses during 2021. January 2021 Table 2.1: Actual sales data for the reading glasses during 2021