If each side of a cube is decreased by 12%, then the percentage decrease in its surface area is:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 22.56%.
Let the original side length of the cube = 10x
Surface area of the cube = 6(10x)2 = 600x2
New side length = 8.8x
New surface area = 6(8.8x)2 = 6(77.44x2) = 464.64x2
Decrease in surface area = 600x2 - 464.64x2 = 135.36x2
Percentage decrease = (135.36x2/600x2) × 100 = 22.56%
Therefore, the percentage decrease in the surface area of the cube is 22.56%.