If the lengths of the edges of a cube are decreased by 20%, the surface area of the cube will decrease by:

If the lengths of the edges of a cube are decreased by 20%, the surface area of the cube will decrease by:
A. 20%.
B. 36%.
C. 40%.
D. 51%.
E. 120%.

Correct Answer: B
Explanation/Reference:
Explanation:
The surface area of a cube is equal to 6e2, where e is the length of an edge of a cube. The surface area of a cube with an edge equal to one unit is 6 cubic units. If the lengths of the edges are decreased by 20%, then the surface area becomes

cubic units, a decrease of
.

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