Question

A cylindrical pillar has a radius of 21 cm and a height of 4 m. Find :
(i) the curved surface area of the pillar
(ii) cost of polishing 36 such cylindrical pillars at the rate of ₹ 12 per m².

Answer 1

Radius of the cylinder = 21 cm

= `21/100 = 2.1`m

Height of the cylinder = 4 m

(i) Curved surface area of the cylinder = `2pirh`

= `2 xx 22/7 xx 2.1 xx 4 = 52.8` m²

(ii) Cost of polishing 1 m² = ₹ 12

Cost of polishing `(36 xx 52.8 "m"^2)`

= ₹ `12 xx 1900.80 = ₹ 22,809.60`