SSC GD 2021 PYQ — Question 69

The correct answer is option 4 i.e. 10.5

Given:

The volume of a right circular cylinder is 8448 cm³ and its curved surface area (in cm²) is $\frac{1}{8}$ of the number representing its volume

Formula used:

Volume of cylinder = πr²h        ---- (1)

Curved surface of cylinder = 2πrh       ---- (2)

Where, r = radius and h = height

Calculations:

Using equation (2)

According to the question,

⇒ 2πrh = (1/8) × 8448

⇒ 2πrh = 1056

⇒ πrh = 1056/2 = 528

We know that,

⇒ πr²h = 8448

⇒ πrh × r = 8448

⇒ 528 × r = 8448

⇒ r = 16

Putting r = 16 in equation (3)

⇒ πrh = 528

⇒ (22/7) × 16 × h = 528

⇒ h = 10.5