Question

find(i) the lateral or 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 1/12 of the steel actually was wasted in making the tank

Answer 1

r=2.1
h=4.5
lateral surface area=2 pi r h
=2*22/7*2.1*4.5=59.4




total stell used= total surface area
=59.4*2*22/7*2.1*2.1=1646.56m^2
metal was used


to find actually steel used u can find 1/12 of this




hope this helps u
if it is right mark as brainliest

Answer 2

Answer:

54.45 cubic m  steel is used .

Step-by-step explanation:

Diameter of Tank = 4.2 m

Radius of tank = $\frac{4.2}{2} = 2.1 m$

Height of tank = 4.5 m

Curved surface area of cylinder = $2 \pi r h$

Curved surface area of cylinder = $2 \times \frac{22}{7} \times 2.1 \times 4.5$

Curved surface area of cylinder = $59.4 m^2$

Now 1/12 of the steel was wasted

So, wasted steel = $\frac{1}{12} \times 59.4 = 4.95 m^2$

Steel used = 59.4 - 4.95= 54.45 cubic m

Hence 54.45 cubic m  steel is used .