Data TruckMaintenance ExpenseMiles DrivenAge of Truck Christopher J. Zappe, Ph.D.: Age of the truck (in years) at the beginning of the year. 1$908.5610,50010 2$751.129,7007 3$793.559,2008...

Please help with the equation and other questions. The file I uploaded only pertains to Problem 4. I have other files for the other problems.


Data TruckMaintenance ExpenseMiles DrivenAge of Truck Christopher J. Zappe, Ph.D.: Age of the truck (in years) at the beginning of the year. 1$908.5610,50010 2$751.129,7007 3$793.559,2008 4$619.618,3009 5$380.116,5005 6$368.724,5002 7$235.323,5002 8$174.932,2003 9$256.301,8002 10$799.5898007 11$436.0466005 12$304.2536001 13$226.8125003 14$179.6831003 15$726.65840010 16$810.5397009 17$142.5318004 18$915.531000011 19$813.4598008 20$803.7899007 21$227.3211001 22$231.4626001 23$839.21103006 Rubric for Assignment 4 Problem 4: (25 points) a. Provide the Excel multiple regression results (5 points) and write down the multiple regression equation (5 points). b. Write down the (two) confidence intervals (5 points). Note: these intervals are part of the regression results from part a. Based on the first interval, would you remove x1 from the equation? (2.5 points). Why? (2.5 points). Based on the second interval, would you remove x2 from the equation? (2.5 points). Why? (2.5 points). Problem 15: (37 points) a. Provide the Excel results (5 points) and write down the multiple regression equation (5 points). Perform a test of significance for each coefficient. Note: there are 4 independent variables so you need to perform 4 tests. You need to state if the variable is significant (10 points, 2.5 points each). Are the signs of the coefficients as expected? First, state the expected sign and then compare it with the actual sign (5 points, 1.25 points each). b. Present a correlation matrix for the independent variables (5 points). Based on this matrix explain if there is evidence of multicollinearity (5 points). If there is multicollinearity, explain how would you remedy this problem (2 points). Problem 21: (40 points) a. Provide the Excel multiple regression results (5 points) and write down the multiple regression equation (5 points). b. For each of the 5 independent variables, determine if it should be excluded from the model AND justify your answer (15 points, 3 points each variable). c. Provide the Excel multiple regression results (5 points) and write down the multiple regression equation (5 points) of a model that excludes the least significant variable (there should now be 4 independent variables). Is this equation better than the one from part a? (2.5 points) Why? (2.5 points). Total: 102 points.