The Great Plains Railroad is interested in studying how fuel consumption is related to the number of railcars for its trains on a certain route between Oklahoma City and Omaha. A random sample of 10 trains on this route has yielded the data in the table below. A scatterplot, a residual plot, and the output from the regression analysis for these data are shown below. a) Is a linear model appropriate for modeling these data? Clearly explain your reasoning. b) Suppose the fuel consumption cost is $25 per unit. Give a point estimate (single value) for the change in the average cost of fuel per mile for each additional railcar attached to a train. Show your work. c) Interpret the value of r^2 in the context of this problem. d) Would it be reasonable to use the fitted regression equation to predict the fuel consumption for a train on this route if the train had 65 railcars? Explain.