If each edge of a cube is increased by 10%, then the percentage increase in its surface area is:
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Correct answer: D
Explanation
The correct answer is option 4 i.e 21%
Let the length of the edge be 100cm.
The surface area will be = 6a2
⇒ 6(100)2 = 600cm2
The length of edge increased by 10%, new edge will be 110
The surface area will be = 6a2
⇒ 6(110)2 = 726cm2
The percentage increase in surface area will be
⇒ {(Final value - initial value) / Initial value} × 100
⇒ (726 - 600) / 600 × 100 = 21%