The volume (in cubic leet) at a black cherry tree can be modeled by the equation '9: 50.2 + 0.4x1 +4.7x2, where x1 is the tree's height (In feet) and x2 is the tree's diameter (in Inches). Use the multiple regression equation to predict the y-values for the values of the independent variables. (a)x1= 73, x2=8.7 ([7) x1 =67, =10,9 (c))(1 = 78, x2 6.7 (d) x1 = 92, X2=202 (a) The predicted volume is cubic feet. (Round in one decimal place as needed.) (b) The predicted volume is cubic feet. (Round to one decimal place as needed.) (c) The predicted volume is cubic feet. (Round to one decimal place as needed.) (d) The predicted volume is cubic feet (Round to one decimal place as needed.)