According to the regression line in exercise the predicted

Question

According to the regression line in Exercise, the predicted amount of gas used when the outside temperature is 20 degree-days is about

(a) 405 cubic feet.  

(b) 320 cubic feet.   

(c) 105 cubic feet.

Exercise:

An owner of a home in the Midwest installed solar panels to reduce heating costs. After installing the solar panels, he measured the amount of natural gas used y (in cubic feet) to heat the home and outside temperature x (in degree-days, where a day's degree-days are the number of degrees its average temperature falls below 65^oF) over a 23-month period. He then computed the least-squares regression line for predicting y from x and found it to be⁹

y = 85 + 16x

Required:

1. How much, on average, does gas used increase for each additional degree-day?

(i) 23 cubic feet

(ii) 85 cubic feet

(iii) 16 cubic feet