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 rs16 per 100 cm2.
Radius of the bowl (r) = 10.5/2 cm = 5.25 cm
Curved surface area of the hemispherical bowl = 2πr2
= (2 × 22/7 × 5.25 × 5.25) cm2
= 173.25 cm2
Rate of tin - plating is = rs16 per 100 cm2
Therefor, cost of 1 cm2 = rs16/100
Total cost of tin-plating the hemisphere bowl = 173.25 × 16/100
= rs 27.72
