2021 · Q51
Eight metallic balls of one centimetre radius each are melted into one ball. The diameter of the new ball is
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- A2 cm
- B6 cm
- C4 cm
- D1 cm
Explanation
When the eight balls are melted, total volume is conserved: 8 x (4/3)πr³ = (4/3)πR³, where r = 1 cm and R is the new ball's radius. Cancelling (4/3)π gives R³ = 8 x 1 = 8, so R = 2 cm. The diameter of the new ball is therefore 2 x 2 = 4 cm. Hence option C is correct.