(5.27) 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 degrees f) over a 23-month period. by looking at the equation of the least-squares regression line (ŷ = 85 + 16x), you can see that the correlation between amount of gas used and degree-days is