Question

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), Y		Thickness of Insulation (inches), X1		Outdoor Temperature (ºF), X2
30.3		4		44
29		12		40
22.8		8		49

On the basis of the sample results, the regression equation is:

Yˆ Y⁢^⁢  = 75.96 – 0.65X₁ – 0.98X₂

a.	How much natural gas can homeowners expect to use per month if they install 4 inches of insulation and the outdoor temperature is 44 degrees F? (Round your answer to 2 decimal places.)
	cubic feet

  

b.	What effect would installing 7 inches of insulation instead of 4 have on the monthly natural gas consumption (assuming the outdoor temperature remains at 44 degrees F)? (Round your answers to 2 decimal places.)
	A  (Click to select)  increase  decrease  of  cubic feet monthly natural gas consumption, down to  cubic feet.

c.	Why are the regression coefficients b1 and b2 negative? Is this logical?

(Click to select)  No  Yes  , logically, as the amount of insulation  (Click to select)  increases  decreases  and outdoor temperature
(Click to select)  increases  decreases  , the consumption of natural gas  (Click to select)  increases  decreases  .

Answer 1

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