Question

Note Take $\mathrm{\pi }=\frac{22}{7}$, unless stated otherwise.
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 ₹ 32 per 100 cm².

Answer 1

Inner radius of the bowl, r = $\frac{10.5}{2}$ = 5.25 cm

∴ Inner curved surface area of the bowl = $2\mathrm{\pi }{r}^2=2\times \frac{22}{7}\times {\left(5.25\right)}^2$ = 173.25 cm²

Rate of tin-plating = ₹ 32 per 100 cm²

∴ Cost of tin-plating the bowl on the inside

= Inner curved surface area of the bowl × Rate of tin-plating

$=173.25\times \frac{32}{100}$

= ₹ 55.44

Thus, the cost of tin-plating the bowl on the inside is ₹ 55.44.