Question

The slant height and base diameter of a conical tomb are $25m$ and $14m$ respectively. Find the cost of whitewashing its curved surface at the rate of $Rs.12$ per $m^2.$

Answer 1

Given
Slant height $=l=25m$
Diameter $=d=14m$
Radius $=r=\frac{d}{2}=\frac{14}{2}=7m$
CSA of cone = $\pi \times r\times l=\frac{22}{7}\times 7\times 25=550m^2$
Cost of white washing $1m^2=Rs12$
Cost of white washing 550 square meters= $(550\times 12)=Rs.6600$