Question:
A hemispherical bowl is made of steel 0.25 cm thick. The inside radius of the bowl is 5 cm. Find the volume of steel used in making the bowl.
Solution:
Inner radius = 5 cm
Outer radius = 5 + 0.25 = 5.25
Volume of steel used = Outer volume-Inner volume
$=2 / 3 \times \pi \times\left((5.25)^{3}-(5)^{3}\right)$
$=2 / 3 \times 22 / 7 \times\left((5.25)^{3}-(5)^{3}\right)$
$=41.282 \mathrm{~cm}^{3}$