Question

Find i) The curved surface area of a closed cylindrical petrol storage
tank that is 4.2m in diameter and 4.5m high.
ii) how much steel was actually used,if 1/12of steel actually wasted making tank ​

Answer 1

EXPLANATION.

Height of the cylinder = 4.5 m.

Diameter of a cylinder = 4.2 m.

Radius of a cylinder = 4.2/2 = 2.1 m.

(ii) = How much steel was actually used

if 1/12 of steel actually wasted making

tank.

Total surface area of tank = 2πr ( r + h).

= 2 X 22/7 X 2.1 ( 2.1 + 4.5 ).

= 2 X 22/7 X 21/10 ( 6.6).

= 22 X 3 X 6.6 / 5.

= 435.6 / 5.

= 87.12 m².

amount of steal used in making tank = x.

Wasted steel = x/12.

T.S.A Of steel = Amount of steal required -

Amount of steal wasted.

→ x - x/12 = 87.12

→ 12x - x / 12 = 87.12

→ 11x / 12 = 87.12

→ 11x = 87.12 X 12

→ 11x = 1045.44

→ x = 95.04 m².

Answer 2

Answer:

curved surface area= 59.4msq

total surface area=87.12msq

Step-by-step explanation:

putting all the values,we get

= curved surface area=2 py rh

=2*22/7*4.2*4.5

=59.4msq

total surface area =2pyr(r+h)

=2*22/7*4.2(4.2+4.5)

=87.12msq