=+56. Efficient design of certain types of municipal waste incinerators requires that information about energy content of the waste be available. The authors of the article “Modeling the Energy Content of Municipal Solid Waste Using Multiple Regression Analysis” (J.

of the Air and Waste Mgmnt. Assoc., 1996: 650–656)

kindly provided us with the accompanying data on y 5 energy content (kcal/kg); the three physical composition variables x1 5 % plastics by weight, x2 5 % paper by weight, and x3 5 % garbage by weight;, and the