Question

Find,the lateral or curved surface area of a closed cylindrical petrol storage tank that is 4.2 metre in diameter and 4.5 metre high, how much Steel was actually used if 1 upon 12 of the Steel actually used was wasted in making the tank.

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Answer 1

Question:—

Find,the lateral or curved surface area of a closed cylindrical petrol storage tank that is 4.2 metre in diameter and 4.5 metre high, how much Steel was actually used if 1 upon 12 of the Steel actually used was wasted in making the tank.

Answer:—

Given: Tank Diameter = 4.2 m

Radius =

$\frac{4.2}{2}=2.1$

Height of the tank = 4.5 m

Formula: Curved surface area of the cylinder = 2πrh = 2 x π x 2.1 x 4.5

= $2\times$ $\frac{22}{7}\times$ $2.1\times$ 4.5= 59.4 m²

Steel was actually used =

$\frac{1}{12}$

x 59.4 ⇒ 4.95

Therefore, steel actually use was wasted in making the tank = 59.4 - 4.95 = 54.45 m.

Answer 2

Given :

• Height = 4.5m
• Diameter = 4.2m

To Find :

• C.S.A of Cylinder
• Steel was actually used if 1/12 of the Steel actually used was wasted in making the tank.

Solution :

$\longmapsto\tt{Radius=2.1m}$

Using Formula :

$\longmapsto\tt\boxed{C.S.A.=2\pi{rh}}$

Putting Values :

$\longmapsto\tt{{2}\times\dfrac{22}{7}\times\dfrac{21}{10}\times\dfrac{45}{10}}$

$\longmapsto\tt{\cancel\dfrac{297}{5}}$

$\longmapsto\tt\bold{{59.4m}^{2}}$

_______________________

Using Formula :

$\longmapsto\tt\boxed{T.S.A=2\pi{rh(r+h)}}$

Putting Values :

$\longmapsto\tt{2\times\dfrac{22}{7}\times\dfrac{21}{10}\times{(2.1+4.5)}}$

$\longmapsto\tt{\dfrac{66}{5}\times\dfrac{(66)}{10}}$

$\longmapsto\tt{6.6\times{6.6}}$

$\longmapsto\tt\bold{{87.12m}^{2}}$

Now :

$\longmapsto\tt\bold{Let\:actually\:steel\:used=x}$

$\longmapsto\tt{Wasted\:Steel=\dfrac{1x}{12}}$

A.T.Q :

$\longmapsto\tt{x-\dfrac{1x}{12}=87.12}$

$\longmapsto\tt{\dfrac{12x-x}{12}=87.12}$

$\longmapsto\tt{\dfrac{11x}{12}=87.12}$

$\longmapsto\tt{x=87.12\times\dfrac{12}{11}}$

$\longmapsto\tt\bold{95.04{m}^{2}}$