Find the volume of the cylinder in which:

(i) Height = 21 cm and Base Radius = 5 cm

(ii) Diameter = 28 cm and Height = 40 cm

By formula, Volume of cylinder = πr²h

(i) Given,

Height (h) = 21 cm and base radius (r) = 5 cm

Volume of cylinder = πr²h

$= \dfrac{22}{7} \times 5^2 \times 21 \\[1em] = \dfrac{22}{7} \times 25 \times 21 \\[1em] = \dfrac{11550}{7} \\[1em] = 1650 \text{ cm}^3.$

Hence, volume of a cylinder = 1650 cm³.

(ii) Given,

Height (h) = 40 cm and Diameter (d) = 28 cm

Radius (r) = $\dfrac{\text{Diameter}}{2} = \dfrac{28}{2} = 14 \text{ cm}$

Volume of cylinder = πr²h

$= \dfrac{22}{7} \times 14^2 \times 40 \\[1em] = \dfrac{22}{7} \times 196 \times 40 \\[1em] = \dfrac{172480}{7} \\[1em] = 24640 \text{ cm}^3.$

Hence, volume of a cylinder = 24640 cm³.