
Phillip R. answered 09/06/14
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I guess a cuboid is a right rectangular prism or box
We need to find the area of the six sides and sum to get the surface area.
2 sides are 40 x 50, 2 sides are 40 x 20, and 2 sides are 20 x 50
S.A. = 2(2000 + 800 + 1000) = 7600 cm3
After 10% increase, S.A. = 2(44 x 55 + 44 x 22 + 22 x 55) = 9196 cm3
(9196 - 7600)/7600 = .21 = 21%