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

$\huge{ \mathtt{ Given-}}$

Diameter of the cylindrical petrol storage tank = 4.2m

Therefore, Radius of the tank =

$\large{ = > \frac{ 4.2}{2} m = 2.1m}$

Height of the tank = 4.5m

$\huge{ \mathtt{ \purple{SOLUTION:-}}}$

$\small\boxed{ \pink{ curved \: surface \: area \: of \: petrol \: storage \: tank = 2\pi \: rh}}$

$\large{ = > 2 \times \frac{22}{7} \times 2.1 \times 4.5}$

$\large{ = > 59.4 {m}^{2} }$

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Total surface area of tank =2πr(r+h)

$\large{ = > 2 \times \frac{22}{7} \times 2.1(2.1 + 4.5)}$

$\large{ = > 44 \times 0.3(2.1 + 4.5)}$

$\large{ = > 87.12 {m}^{2} }$

Let amount of steel used in making the tank =x

Therefore,steel wasted in making the tank = x/12

$\huge{ \mathtt{ \orange{Given \: that:}}}$

Amount of steel required - Amount of steel wasted = Total surface area of tank

$\large{ = > x - \frac{x}{12} = 87.12}$

$\large{ = > \frac{11}{12} x = 87.12}$

$\large{ = > x = \frac{12}{11} \times 87.12}$

$\large{ = > x = 95.04 {m}^{2} }$

Therefore,95.04$\large{m}^{2} }$ steel was used in actual while making such a tank.

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$\large{ \mathtt{ \bold{ \red{Thanks...}}}}$

Answer 2

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.