The file HHIncome contains data from a sample of 25 U.S. cities. The variables collected for this sample are city median household income ($); unemployment rate (%); median home value ($); number of violent crimes per 100,000 residents; average commuter travel time (minutes); and livability score, a rating on a scale of 0 to 100 that rates the overall livability of the city. (Data extracted from "America's 50 Best Cities to Live," bit.ly/1uGQIYh and "Livability Index," bit.ly/1Qbd6oj.) Develop the most appropriate multiple regression model to predict median city household income. Be sure to perform a thorough residual analysis and provide a detailed explanation of the results as part of your answer.