Suppose that we also have data on a second treadmill, made by LifeFitness. An indicator variable for brand of treadmill, say Treadmill = 1 for Cybex and Treadmill= 0 for LifeFitness, is created for a new model. If the three explanatory variables above and the new indicator variable Treadmill were used to predict Calories, how many parameters would need to be estimated in the new multiple regression model?
(a) 4 (b) 5 (c) 6