Question

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
of the tank. (anewer quickly and steps in order )​

Answer 1

Answer:

The amount of steel used = 94.38 $m^{2}$

Step-by-step explanation:

Height of the tank = 4.5 m.

Diameter of the tank = 4.2 m.

But,

radius = $\frac{diameter}{2}$

           = $\frac{4.2}{2}$

radius  = 2.1 m

Total surface area of a cylinder = 2$\pi$rh + 2$\pi$$r^{2}$

                                      = 2$\pi$r(r + h)

                                      = 2 x $\frac{22}{7}$ x 2.1 (2.1 + 4.5)

                                      = 44 x 0.3 (6.6)

                                      = 87.12

Total surface area of a cylinder = 87.12 $m^{2}$

Since $\frac{1}{12}$ of the steel was wasted, then;

$\frac{1}{12}$ x 87.12 = 7.26 $m^{2}$

Actual area of steel sheet used = 87.12 + 7.26

                                                     = 94.38 $m^{2}$

Thus, 94.38 $m^{2}$ of steel was used in making the tank.