A trucking company considered a multiple regression model for relating the dependent variable y = total daily travel time for one of its drivers (hours) to the predictors x1 = distance traveled (miles) and x2= the number of deliveries made. Suppose that the model equation is
a. What is the mean value of travel time when distance traveled is 50 miles and three deliveries are made?
b. How would you interpret ß1 = .060, the coefficient of the predictor x1? What is the interpretation of ß2 = .900?
c. If σ = .5 hour, what is the probability that travel time will be at most 6 hours when three deliveries are made and the distance traveled is 50 miles?