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=88 + 15x

The predicted amount of gas used when the outside temperature is 18 degree-days

is about: ___ cubic feet. (Answer to the nearest cubic foot.)

Solution

As

y = 88 + 15x

where x = the temperature
y = amount of natural gas

Thus, if x = 18,

y = 88 + 15(18) = 358 cubic feet [ANSWER]