2019 · Q66
Three copper spheres of radii 3 cm, 4 cm and 5 cm are melted to form a large sphere. What is its radius?
Elementary MathematicsMensuration
- A12 cm
- B10 cm
- C8 cm
- D6 cm
Explanation
Melting conserves volume: (4/3)πR³ = (4/3)π(3³ + 4³ + 5³) = (4/3)π(27 + 64 + 125) = (4/3)π·216, so R³ = 216 and R = 6 cm. The answer is (D).