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August 31, 2014

August 31, 2014

Posted by **Kat** on Thursday, May 5, 2011 at 6:22pm.

I am tearing my hair out over this question! Please help asap!

- Math -
**Reiny**, Thursday, May 5, 2011 at 6:29pmThe surface areas of similar solids is proportional to the square of their sides

since the ratio of sides is 1 : 3

their surface areas have the ratio 1^2 : 3^2 or 1 : 9

so the surface area is 9(10.4) or 93.6

or

original width = x

original length = y

original heigt = z

original surface area = 2(xy) + 2(xz) + 2(yz)

= 2(xy + xz + yz)

new width = 3x

new length = 3y

new height = 3z

new surface area = 2(9xy) + 2(9xz) + 2(9yz)

= 18(xy + xz + yz)

ratio of new to old = 18(xy + xz + yz) : 2(xy + xz + yz)

= 9 : 1

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