Question

A bus stop is barricaded from the remaining part of the road, by using $50$ hollow cones made of recycles cardboard. Each cone has a base diameter of $40cm$ and height $1m$. If the outer side of each of the cones is to be painted and the cost of painting is $Rs12per{m}^2$, what will be the cost of painting all these cones? (Use $\pi =3.14$ and take $\sqrt{1.04}=1.02$)

Answer 1

Total no. of cone $=50$

Cost $=12/m^2$

Radius of cone $r=\frac{40}{2}=20cm=0.2m$

$\Rightarrow h=1m$

$\Rightarrow$ Slant height $l=\sqrt{r^2+h^2}=\sqrt{{0.2}^2+1^2}$

$l=\sqrt{1.04}$

$l=1.02m$

$\Rightarrow$ Total surface area $S=50\times \pi rl$

$=50\times 3.14\times 0.2\times 1.02$

$=32.028m^2$

$\Rightarrow$ Total cost $=12\times 32.028$

$=384.336Rs.$

Hence, the answer is $384.336Rs.$