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A bigger ball of radius of 7 cm is recast into smaller balls of radius of 2 cm each, in this process 20% of the material is wasted, then how many such complete spherical smaller balls can be made?

A bigger ball of radius of 7 cm is recast into smaller balls of radius of 2 cm each, in this process 20% of the material is wasted, then how many such complete spherical smaller balls can be made? Correct Answer 34

Let the number of small spheres be is n.

Radius of bigger ball R = 7 cm and radius of smaller ball r = 2 cm

As we know, volume of sphere = 4/3 × π × r3

⇒ 4/3 × π × R3 × = n × 4/3 × π × r3

⇒ R3 × = n × r3

⇒ 73 × 0.8 = n × 23

⇒ n = (343 × 0.8)/8 = 343 × 0.1 = 34.3

So, the number of complete balls is 34.

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