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in cubic feet

by sanju09 » Wed Mar 04, 2009 4:53 am
The rectangular solid attached has surface area 112 square feet. What is the volume, in cubic feet, of the solid?

(A) 30
(B) 45
(C) 60
(D) 72
(E) 90
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by truplayer256 » Wed Mar 04, 2009 4:56 am
(10x)(2)+(3x)(2)+60=112
20x+6x=52
x=2
V=lwh
V=10*2*3=60 C
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by quocbao » Wed Mar 04, 2009 7:49 am
I got C too.

Surface areas = (10 x 3 + 10 x X + 3 x X ) x 2 = 112
==> X = 2

Volume = 10 x 2 x 3 = 60
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Re: in cubic feet

by marcusking » Wed Mar 04, 2009 8:58 am
sanju09 wrote:The rectangular solid attached has surface area 112 square feet. What is the volume, in cubic feet, of the solid?

(A) 30
(B) 45
(C) 60
(D) 72
(E) 90
SA = 2(10*3) + 2(10*x) + 2(3*x)
112 = 60 + 20x + 6x
52 = 26x
x = 2

Volume = 10 * 3 * 2
Volume = 60 C.

Please start posting the OA.
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by sanju09 » Thu Mar 05, 2009 2:44 am
The surface area of the rectangular solid is the sum of the areas of its six faces. The rectangular solid has two faces with area 30 square feet each, two faces with area 10x square feet each, and two faces with area 3x square feet each. Therefore, its surface area is 2(30 + 10x + 3x) square feet. Since the surface area is given to be 112 square feet, it follows that 60 + 26x = 112, and x = 2. Thus the width of the rectangular solid is 2 feet.

The volume of the solid is given by the product of its length, width, and height. Therefore, the volume is (10 feet)(2 feet)(3 feet), or 60 cubic feet. Thus the correct answer is [spoiler](C)[/spoiler].
The mind is everything. What you think you become. -Lord Buddha



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