Question

A hemispherical bowl made of brass has inner diameter $10.5$cm. Find the cost of tin-plating it on the inside at the rate of Rs. $16$ per $100$ $c{m}^2$.

Answer 1

$d=10.5cm$

$r=\frac{d}{2}=\frac{10.5}{2}=5.25$

Curved surface area of hemisphere$=2\pi r^2=2\pi (5.25{)}^2=173.25c{m}^2$

Cost of tin plating $100c{m}^2=16Rs$

Cost of tin plating $1c{m}^2=\frac{16}{100}Rs$

Cost of tin plating $173.25c{m}^2=\frac{16}{100}\times 173.25=27.72Rs$

Cost of tin plating$=27.72Rs$