Question

the outer diameter of a pipe is 70cm and has Length of 21m. find the cost of polishing its outer surface at the rate of Rs.10per m.sq

Answer 1

given diameter of the pipe =d=70cm
radius =r=d/2=70/2=35cm
length =h =21m =2100cm
surface area of the pipe=surface area of the cylinder

= 2pi*r*h
=2*22/7*35*2100
=462000cm^2
=46.2m^2
cost of polishing 1 square m pipe = Rs 10
cost of polishing the pipe =Rs 10×46.2
=Rs462