T 1. Butler Pools and Spa sells pool supplies in Southern California. In that industry, Butler sales show seasonality based on 3 seasons (Winter-Jan to April, Summer-May to August, and Fall- September to December). Sales data for last 4 years is given below: Year 1 2 Winter (W) 32 38 45 52 Summer (S) 75 86 97 108 Fall (F) 52 62 73 84 (a) Plot this data and clearly write what type of pattern is present in this data (b) Use Dummy variables to solve this and clearly write the regression equation (c) Use the regression equation to provide forecast for all 3 seasons of 5th year.