Question: Cooling method for gas turbines. The Journal of Engineering for Gas Turbines and Power (January 2005) published a study of a high-pressure inlet fogging method for a gas turbine engine. The heat rate (kilojoules per kilowatt per hour) was measured for each in a sample of 67 gas turbines augmented with high-pressure inlet fogging. In addition, several other variables were measured, including cycle speed (revolutions per minute), inlet temperature (?C), exhaust gas temperature (?C), cycle pressure ratio, and air mass flow rate (kilograms per second). The data are saved in the GASTURBINE file. (The first and last five observations are listed in the table.) Consider using these variables as predictors of heat rate (y) in a regression model. Construct scatterplots relating heat rate to each of the independent variables. Based on the graphs, hypothesize a polynomial model relating y to each independent variable.