Tony is investigating the relationship between his daily energy bill in pounds (eee) and the average daily temperature in degrees (ttt) each day in the winter.
He finds that the equation of the regression line is e=7.3−0.4te = 7.3 - 0.4te=7.3−0.4t
Describe the correlation between Tony's bill and the average daily temperature.
Give an interpretation of the gradient of this regression line.
Explain why this model might not be appropriate for Tony's energy bill in the summer.