Simple linear regression model: y is salary and x is education. What is the residual for the 4th observation. If the observed salary for that sample point is $50000 and predicted salary is $47000? A. $4500 B. $3000 C. $9750 Question 2: R-Squared (=the coefficient of determination) is A. the ratio of the total variation compared to the residual variation B. the product of the explained variation and the residual variation C. the ratio of the explained variation compared to the total variation