Reference no: EM131058172

To study the energy savings due to adding solar heating panels to a house, researchers measured the natural gas consumption of the house for more than a year, then installed solar panels and observed the natural gas consumption for almost two years. The explanatory variablex is degree-days per day during the several weeks covered by each observation, and the response variabley is gas consumption (in hundreds of cubic feet) per day during the same period. The figure below plotsy againstx, with separate symbols for observations taken before and after the installation of the solar panels. The least-squares regression lines were computed separately for the before and after data and are drawn on the plot. The regression lines are as follows.

Before:	= 1.089 + 0.189x
After:	= 0.853 + 0.157x

(b) About how much additional natural gas was consumed per day for each additional degree-day before the panels were added? (Enter your answer to three decimal places.)

c) The daily average temperature during January in this location is about 30 degrees, which corresponds to 35 degree-days per day. Use the regression lines to predict daily gas usage for a day with 35 degree-days before and after installation of the panels. (Enter your answers to three decimal places.)