Question

In a hollow cylinder, the sum of the external and internal radii is 14 cm and the width is 4 cm. If its height is 20 cm, the volume of the material in it is

Options

• 5600π cm³

• 11200π cm³

• 56π cm³

• 3600π cm³

Answer 1

11200π cm³

Explanation;

Hint:

Here, let the external radius be "R" and the internal radius be "r"

R + r = 14  ...(1)

Width (R – r) = 4  ...(2)

Height of the hollow cylinder = 20 cm

Volume of the hollow cylinder = πh × (R² – r²)

= πh(R + r) (R – r)

= π × 20 (14) × 4

= π × 1120

= 1120π cm³