- 2
- 4
- 16
- 8

Option 4 : 8

**Given:**

The volume of the small sphere = 32π/3

number of small sphere = 64

**Formula used:**

The volume of sphere = 4/3 π r^{3}

**Concept used:**

When the number of the small spheres is melted and a new sphere is cast then the volume of the casted sphere is the same as the melted sphere.

**Calculation:**

The total volume of melted sphere = 64 × 32π/3

Volume of big sphere = 64 × 32π/3

⇒ 4/3 π r3 = 64 × 32π/3

⇒ r3 = 64 × 8

⇒ r = 8

**∴ The radius of big sphere is 8 cm**

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