Question

A cylindrical pillar has radius 21 cm and height 4 m. Find:

i) The curved surface arae of the pillar

ii) Cost of polishing 36 such cylindrical pillars at the rate of Rs. 12 per $m^2$

Answer 1

Radius of the cylinder = 21 cm
$=\frac{21}{100}=2.1m$
Height of the cylinder = 4m.
i) Curved surface area of the cylinder $=2\pi rh$
$=2\times \frac{22}{7}\times 2.1\times 4=52.8m^2$

ii) Cost of polishing $1m^2=Rs.12$
Cost of polishing $36\times 52.8m^2$
$=Rs.12\times 1900.80=Rs.22809.60$