Cellulon, a manufacturer of home insulation, wants to develop
guidelines for builders and consumers on how the thickness of the
insulation in the attic of a home and the outdoor temperature
affect natural gas consumption. In the laboratory, it varied the
insulation thickness and temperature. A few of the findings
are:
| Monthly Natural Gas Consumption (cubic feet), | Thickness of Insulation (inches), | Outdoor Temperature (ºF), | |||
| y | x1 | x2 | |||
| 30.3 | 6 | 40 | |||
| 26.9 | 12 | 40 | |||
| 22.1 | 8 | 49 | |||
On the basis of the sample results, the regression equation
is:
yˆ yâ¢^â¢â€‰ = 62.65 – 1.86x1 –
0.52x2
1. How much natural gas can homeowners expect to use
per month if they install 6 inches of insulation and the outdoor
temperature is 40 degrees F? (Round your answer to 2
decimal places.)
2. What effect would installing 7 inches of
insulation instead of 6 have on the monthly natural gas consumption
(assuming the outdoor temperature remains at 40 degrees F)?
(Round your answers to 2 decimal places.)
3. Why are the regression coefficients
b1 and b2 negative? Is this
logical?
