2. The quarterly sales data (number of copies sold) for a college textbook over the past two years follow. a) Apply Winter's method to forecast quarterly sales in 2020 (i.e compute F0.1,F0.2,F0.3 and F0,4). (15 pts.) b) Suppose that the actual sales data for the 1st quarter of 2020 is observed as 230 . Update the intercept, slope and seasonality indexes and forecast sales in 2nd,3rd and 4th quarters of 2020.(=0.2,=0.1,=0.1)(15 pts. )