(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.
Height (h) of cylindrical tank = 4.5 m
Radius (r) of the circular end of cylindrical tank = (4.2/2)m = 2.1m
(i) Lateral or curved surface area of tank = 2πrh
= (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)
= (44 × 0.3 × 6.6) m2
= 87.12 m2
Let A m2 steel sheet be actually used in making the tank.
⇒ A = 95.04 m2
Therefore, 95.04 m2 steel was used in actual while making such a tank.
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