Question

find
1.the total surface area of a closed cylinder petrol storage tank whose diameter 4.2m And height4. 5m
2.How much steel sheet was actually used,if 1/12 of the steel was wasted in making the tank​

Answer 1

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(i)Diameter of a cylindrical(closed) petrol tank=4.2 m

Radius=

2

4.2

=2.1 m

Height=4.5 m

Curved Surface area=2πrh=2×

7

22

×2.1×4.5=59.4sq.m

(ii)Total surface area=2πr(r+h)=2×

7

22

×2.1×(2.1+4.5)=2×

7

22

×2.1×6.6=87.12 sq.m

Let the amount of steel used in making the tank=x

Steel wasted=

12

x

Given:Amount of steel required−Amount of steel wasted=T.S.A of the tank.

⇒x−

12

x

=87.12

⇒

12

12x−x

=87.12

⇒

12

11x

=87.12

⇒x=

11

12

×87.12=95.04sq.m

∴95.04sq.m steel was used in actual while making such a tank.