Hi, Could you please check if I did this correctly. I feel that 'b" is wrong. I don't understand how Seasonal Factor multiplied by the fitted line formula gives me the weighted seasonal forecast? Is it the 'Forecase including trend' I'm using?

6. The quarterly sales in units for "Retail sale Sports" for the last two years are as follows: Quarter Year 1 Year 2 440 560 II 460 490 III 420 500 IV 390 400 Using linear regression, a straight line was fitted to the sales data. Assume that the equation of the fitted line is Y = 420 + 6 x t. The first quarter in the data is labeled t =1. a) Calculate seasonal indexes for this product using the fitted line approach. Quarter 285.38 Year 1 FIT = Y = 420 +6 x t Ratio of Seasonal Actual Amount Actual / trend Factor 140 426 1.03 1.14 N 460 432 1.06 1.07 420 438 0.96 1.02 390 444 0.88 0.87 Year 2 5 560 450 1.24 1.14 a 490 456 1.07 1.07 500 462 1.08 1.02 400 468 0.85 0.87 b) Using the fitted line and seasonal indexes you have just calculated, forecast sales in each quarter of year 3. MGSC 368v10 Assignment 1 April 2019 Year 3 quarter sales forecast including trend. FIT = Y = [420 + 6 x t] (seasonal Factor) Year 3 Q1 : t=9 FIT = Y = [420 + 6 x 9] 1.14 FIT = 540.36 Q2 : t=10 FIT =Y = [420 + 6 x 10] 1.07 FIT = 513.6 Q3 : t=11 FIT =Y = [420 + 6 x 11] 1.02 FIT = 495.72 Q4 : t=12 FIT = Y = [420 + 6 x 12] 0.87 FIT = 428.04