SOLUTION: Solve. A homeowner wishes to insulate her attic with fiberglass insulation to conserve energy. The insulation comes in 40-cm wide rolls that are cut to fit between the rafters i

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Question 118092: Solve.
A homeowner wishes to insulate her attic with fiberglass insulation to conserve energy. The insulation comes in 40-cm wide rolls that are cut to fit between the rafters in the attic. If the roof is 7 m from peak to eave and the attic space is 3 m high at the peak, how long does each of the pieces of insulation need to be? Round to the nearest tenth.

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!
One half of the length that you are trying to calculate is the long leg of a right triangle with a short leg of 3 meters and a hypotenuse of 7 meters. Using Pythagoras, b=sqrt%287%5E2-3%5E2%29=sqrt%2849-9%29=sqrt%2840%29=2%2Asqrt%2810%29.

Rounded to the nearest tenth: 2%2Asqrt%2810%29=6.3 meters.

By the way, it is inappropriate to express this answer to the nearest tenth. When expressing the result of calculations based on measurements, the result cannot be any more precise than the LEAST precise measurement given. Since both of the length measurements given in problem were to the nearest whole meter, the answer should also be expressed to the nearest whole meter. If an answer to the nearest tenth were required, then the measurements should have been expressed as 7.0 meters and 3.0 meters respectively.

Note that there is a vast difference between saying something measures 7 meters and saying that it measures 7.0 meters. If you say something measures 7 meters, you are only guaranteeing that the actual length is in the interval 6.5%3C=x%3C7.5, whereas 7.0 ensures the actual length is in the interval 6.95%3C=x%3C7.05 -- a rather significant difference indeed.

Hope that helps.
John