In an effort to explain to customers why their electricity bills have been so high lately, and how customers could save money by reducing the thermostat settings on both space heaters and water heaters, a public utility commission has collected total kilowatt consumption figures for last year’s winter months, as well as thermostat settings on space and water heaters, for 100 homes.

a. Determine the regression equation.

b. Determine the coefficient of determination and describe what it tells you.

c. Test the validity of the model.

d. Find the 95% interval of the electricity consumption of a house whose space heater thermostat is set at 70 and whose water heater thermostat is set at 130.

e. Calculate the 95% interval of the average electricity consumption for houses whose space heater thermostat is set at 70 and whose water heater thermostat is set at 130.