Question

Find

(i) The lateral or curved surface area of a closed cylindrical petrol storage tank that is 4.2 m in diameter and 4.5 m high.

(ii) How much steel was actually used, if 1/12 of the steel actually used was wasted in making the tank.  [ Assume π = 22/7 ]

Answer 1

Height (h) of cylindrical tank = 4.5 m

Radius (r) of the circular end of cylindrical tank = (4.2/2) m = 2.1 m

(i) Lateral or curved surface area of tank = 2πrh 

= (2 x 22/7 x 2.1 x 4.5) m²

= (44 × 0.3 × 4.5) m²

= 59.4 m²

Therefore, CSA of tank is 59.4 m².

(ii) Total surface area of tank = 2πr (r + h)

= [2 x 22/7 x 2.1 x (2.1 x 4.5)] m²

= (44 × 0.3 × 6.6) m²

= 87.12 m²

Let A m² steel sheet be actually used in making the tank.

Therefore, 95.04 m² steel was used in actual while making such a tank.