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A sphere of radius 7 cm is melted and recast into small spheres of radius 2 cm each. How many such spheres can be made?

A sphere of radius 7 cm is melted and recast into small spheres of radius 2 cm each. How many such spheres can be made? Correct Answer 42

Volume of sphere = (4/3)πr3

Volume of large sphere = 4/3 × π × 7 × 7 × 7 = (4π/3) × 73

Volume of small sphere = (4π/3) × 23

Then, let B be the number of spheres.

⇒ (4π/3) × 73 = B × (4π/3) × 23)

⇒ B = 42

There are 42 spheres.

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