Objective 4.2: Given the least-squares regression equation, calculate a predicted value for the response variable and its residual. One use of the least-squares regression equation is to predict the value of the response variable for different values of the explanatory variable. To do so, substitute the value of the explanatory variable into the least-squares regression equation for x. Learn by Doing The least-squares regression equation in the Arby's Sandwich example is y = 67.8448 +1.9019x, where x = serving size (in grams), and y = predicted number of calories. Predict the number of calories in an Arby's sandwich with a serving size of 325 grams. Report your answer to FOUR decimal places. 685.71 calories