Question

Find how much steel was actually used, if $\frac{1}{12}$ of the steel actually used was wasted in making the tank shown in the figure.(Assume $\pi =\frac{22}{7}$)

Answer 1

Given:$h=4.5$m,$r=2.1$m

Total surface area of tank$=2\pi r(r+h)$

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

$=2\times \frac{22}{7}\times 2.1\times 6.6=87.12m^2$

Let amount of steel used in making the tank $x$

Steel wasted$=\frac{x}{12}$

Given that:Amount of steel required$-$Amount of steel wasted$=$TSA of tank.

$\Rightarrow x-\frac{x}{12}=87.12$

$\Rightarrow \frac{11x}{12}=87.12$

$\Rightarrow x=\frac{12}{11}\times 87.12=95.04m^2$

$\therefore ,95.04m^2$ steel was used in actual while making such a tank.