Question

A cylinder vessal open at the top has diameter $20cm$ and height $14cm$. Find the cost of tin-plating it on the inside at the rate of $50paisa$ per hundred square centimeter.

Answer 1

diameter $=20cm$

radius $=10cm$

ht $=14cm$

Area of cylindrical vessel $=2\pi rh+\pi r^2=2\pi \times 10\times 14+\pi \times 10\times 10$

$=280\pi +100\pi$

$=380\pi c{m}^2$

Cost per $100c{m}^2=50paise=Rs.0.005/c{m}^2$

$\therefore$ Total cost$=Rs.0.005\times 380\pi$

$=Rs.0.005\times \frac{8360}{7}$

$=Rs.5.97$