A bus stop is barricaded from the remaining part of the road, by using 50 hollow cones made of recycled card-board. 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 painting all these cones `(U s epi=3. 14a n dsqrt(1. 04)=1. 02))`

Explanation

Height `h=1m`
Radius `r=40/2=20cm=0.2m`
Slant height `l^2=h^2+r^2=1^2+0.2^2`
`=>l=sqrt(1+0.04)=sqrt1.04=1.02m` [Given]
`=>`Curved surface area of `1` cone`=pirl=(3.14xx0.2xx1.02)m^2=0.64046m^2`
`=>` Curved surface area of `50` cones`=50xx0.64046=32.028m^2`
Cost of painting of `1m^2=Rs.12`
`=>` Cost of painting`=(12xx32.028)=Rs. 384.336≈Rs. 384.34`
`:.` Cost of painting `50` cones`=Rs.384.34`