Question

9. Find(1) The total surface area of a closed cylindrical petrol storage tank whose diameter
4.2 m and height 4.5 m.
(i) How much steel sheet was actually used,if 1/12 of the steel was wasted in making the tank.​

Answer 1

Answer:

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