3. A company provides the following data: Sales figures and advertising expenses for the stores are provided in the table below. Sales are given in millions of dollars; advertising expenses are in tens of thousands of dollars. a) Calculate a regression line for the data. b) What is your forecast of sales for a store with advertising spending of $250,000? $600,000? Store Advertising Sales 1 14 16 2 21 13 3 5 15 4 26 15 5 34 ks 16 38 28 7 B2 7 18 31 22 19 B6 Ks 10 3 30 11 144 14 12 19 15