Question

Find

(i) The total surface area of a closed cylindrical petrol storage tank whose diameter

4.2 m. and height 4.5 m.

(ii) How much steel sheet was actually used, if 12

1

of the steel was wasted in making

the tank.​

Answer 1

Step-by-step explanation:

Given

Diameter of the cylinders=4.2m

∴ Radius of the cylinders, r =

2

4.2

=2.1m

Height of the cylinders, h=4.5m

Thus, the total surface area of the closed cylindrical

petrol tank=2πrh+2πr

2

=2π(2.1)(4.5)+2.π(2.1)

2

=2.

7

22

×2.1×4.5+2×

7

22

×2.1×2.1[π=

7

22

]

=59.4+27.72

=87.12m^2

2nd Part

Given, a closed cylindrical petrol tank.

The diameter of the tank =

Height of the tank =

Now, Total surface area of the tank =

Now, let

of steel sheet be actually used in making the tank

Since

of steel was wasted, the left

of the total steel sheet was used to made the tank.

The total surface area of the tank =

Therefore,

of steel was actually used in making the tank.

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