For 2005, the consumption of gasoline was measured in the 50 states and the District of Columbia in the United States by the Federal Highway Administration. The response y is the consumption of...

For 2005, the consumption of gasoline was measured in the 50 states and the

District of Columbia in the United States by the Federal Highway Administration. The response y is the consumption of gallons of gasoline per population of 16 years olds and older. Consider the following four predictor

variables—x1: state gasoline tax (cents per gallon), x2: per capita income

(1000s of dollars), x3: paved highways (1000s of miles), and x4: licensed