Answer:
442 ft²
Explanation:
The amount of insulation needed is the amount that covers the area of the side walls and the ceiling. The area of the side walls is the product of the perimeter and height. The area of the ceiling is the product of length and width.
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Lateral area = Ph = 2(L+W)h = 2(15 ft +8 ft)(7 ft) = 322 ft²
Ceiling area = LW = (15 ft)(8 ft) = 120 ft²
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Insulation needed = lateral area + ceiling area = 322 ft² +120 ft²
Insulation needed = 442 ft²