Cengiz Haksever runs an Istanbul high-end jewelry shop. He advertises weekly in local Turkish newspapers and is thinking of increasing his ad budget. Before doing so, he decides to evaluate the past effectiveness of these ads. Five weeks are sampled, and the data are shown in the table below Week # Total Advertisement Budget (in 1000s TL) Sales (in 10000s TL) 11 6 10 6 12 1 2 3 4 5 5 3 7 2 8 a) Derive the one variate linear regression expression (8 points) b) Based on that make a forecast for your sales level if you plan to spend on advertising 7500 TL next week. (5 points)