Question

A bus stop is barricaded from the remaining part of the road, by using 50 hollow cones made of recycled 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 Rs $12$ per $m^2$, what will be the cost of the painting all these cones? $(Use\pi =3.14andtake\sqrt{1.04}=1.02)$

Answer 1

Given total no. of cones $=50$.

Dimension of 1 cone i.e. radius $=20cm$

height $=1m$

now CSA of 1 cone $=\pi rl=\pi r\sqrt{h^2+r^2}$

$=\pi \times 20\sqrt{10000+400}=20\pi \times 102$

CSA of cone $=0.6405m^2$

Total area $=50\times 0.64=32m^2$

Cost of painting $=Rs.12/m^2$

Total cost $=12\times 32$

Total cost $=384RS.$]