A sphere of radius 5 cm is melted and recast into spheres of radius 2 cm each. How many such spheres can be made?

A sphere of radius 5 cm is melted and recast into spheres of radius 2 cm each. How many such spheres can be made? Correct Answer 15

Let the number of small spheres be n.

According to the question

⇒ (4/3) × π × R³ = n × 4/3 × π × r³

⇒ R³ = n × r³

⇒ 5³ = n × 2³

⇒ n = 125/8 = 15.625

Therefore 15 complete spheres can be made with some extra molten material left.

Mistake PointsIn this question does not take the 16 as an approx answer, because such type of question is always 15.625, take the integer value only. 15 is the right answer.