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Question
Find the lateral curved surface area of a cylinderical petrol storage tank that is 4.2 m in diameter and 4.5 m high. How much steel was actually used, if `1/12` of steel actually used was wasted in making the closed tank?
Solution
Height (h) cylindrical tank=4.5m
Radius (r) of circular end of cylindrical tank =` 4.2/2m=2.1 m`
(1) Lateral or curved surface area of tank = `2pirh`
⇒` 2xx3.14xx2.1xx4.5m^2`
= `59.4m^2`
(2) Total surface area of tank = `2pir(r+h)`
⇒ `2[22/7]xx2.1(2.1+4.5)m^2`
= `87.12m^2`
Let A ` m^2` steel sheet be actually used in making the tank
`∴ A(1-1/12)=87.12m^2`
⇒ `A= (12/pixx87.12)m^2`
⇒ `A=95.04m^2`
Thus, ` 95.04m^2` steel was used in actual while making the tank.
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