#### Answer

a

#### Work Step by Step

The $R$ factor is directly related to the thickness of the insulation. Since the thickness doubled, we can conclude that the $R$ factor must double as well. Thus, $\fbox{a}$ is the correct answer.

Published by
Pearson

ISBN 10:
0-134-98855-8

ISBN 13:
978-0-13498-855-9

a

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