How can we answer this using POM QM software?

An air conditioning and heating repair firm conducted a study to determine if the average outside temperature could be used to predict the cost of an electric bill for homes during the winter months in Houston, Texas. Y = 228.19 - 1.45X, where Y = monthly cost, X = average outside air temperature

(a) If the temperature averaged 48 degrees during December, what is the forecasted cost of December's electric bill?

(b) If the temperature averaged 38 degrees during January, what is the forecasted cost of January's electric bill?

Model building :

1. What's Formula for r2 =

2. What are Stepwise regression (forward and backward stepwise procedure): - Explain in 3-4 lines max.