Question

A hemispherical bowl is made of steel of $0.25cm$ thickness. The inner radius of the bowl is $5cm$. The volume of steel used is ...........

• A. $42.15{cm}^3$
• B. $41.52{cm}^3$
• C. $41.25{cm}^3$
• D. none of these

Answer 1

The correct option is C $41.25{cm}^3$

Given, inner radius of bowl $=5cm$ and bowl thickness $=0.25cm$

Volume of a hollow hemisphere of outer Radius R and inner radius r $=\frac{2}{3}\pi (R^2-r^3)$
Outer radius of the bowl $=5+0.25=5.25cm$
Hence, volume of steel used $=\frac{2}{3}\times \pi \times ({5.25}^3-5^3)=41.25{cm}^3$