An owner of a home in the Midwest installed solar panels to

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 be:

yˆ=84 + 17x.

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

Answer : _____ cubic feet.

(Give your answer as a whole number.)

Solution

The coefficient of x is the average increase, for each additional degree-day

Hence 17 cubic feet is the average increase