Find

(i) The lateral or curved surface area of a closed cylindrical petrol storage tank that is4.2 m in diameter and 4.5 m high.


(ii) How much steel was actually used, ifof the steel actually used was wasted in making the tank


Height (h) of cylindrical tank = 4.5 m

Radius (r) = () = 2.1 m


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


= 2 * * 2.1 * 4.5


= (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 * * 2.1 * (2.1 + 4.5) m2


= (44 × 0.3 × 6.6) m2


= 87.12 m2


Let x m2 steel sheet be actually used in making the tank


x (1 - ) = 87.12 m2


x = ( * 87.12) m2


x = 95.04 m2


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


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