2021 · Q35
A metal solid cube of edge 24 cm is melted and made into three small cubes. If the edges of two small cubes are 12 cm and 16 cm, then what is the surface area of the third small cube?
Elementary MathematicsMensuration
- A1200 cm²
- B1800 cm²
- C2400 cm²
- D3600 cm²
Explanation
The third cube's volume is 24³ − 12³ − 16³ = 13824 − 1728 − 4096 = 8000, so its edge is 20 cm. Its surface area is 6·20² = 2400 cm². Hence option C.