Three solid cubes of metal have sides 6 cm, 8 cm and 10 cm, respectively. They are melted to form a new cube. What is the surface area of this new cube?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 864 cm2.
Volume of cube = (side)3
Surface area of cube = 6(side)2
When a solid substance is melted to form a new solid substance then their volumes are numerically equal.
According to the given question,
Volumes of three cubes to be melyed = Volume of the new cube formed
Let the side of the new cube to be formed be x cm.
⇒ 63 + 83 + 103 = x3
⇒ x3 = 216 + 512 + 1000
⇒ x3 = 1728
⇒ x = 12 cm
Now, surface area of new cube = 6(12)2
⇒ 6 × 144 = 864 cm2
Hence the surface area of this new cube is 864 cm2.