- 924
- 920
- 926
- 922

Option 1 : 924

**Given:**

The diameter of a sphere and cylinder = 21 cm

The volume of a cylinder = Volume of a sphere

**Formula used**:

Volume of a cylinder = πr^{2}h

The volume of a sphere = (4/3)πr^{3}

The curved surface area of a cylinder = 2πrh

**Calculation:**

The diameter of a sphere and cylinder = 21 cm

Radius = 21/2 cm

The volume of a cylinder = Volume of a sphere

⇒ (4/3)πr^{3} = πr2h

⇒ (4/3) × (21/2) × (21/2) × (21/2) = (21/2) × (21/2) × h

⇒ h = 14 cm

Now,

The curved surface area of cylinder = 2πrh

2 × (22/7) × (21/2) × 14

⇒ 924 cm^{2}

**∴ The curved surface area of the cylinder is 924 cm ^{2}**.

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