A tent in the form of a cylinder of diameter 4.2m and height 4m surmounted by a cone of equal base and height 2.8m. The capacity of the tent and the cost of canvas to making the tent at Rs.100 per square meter is

Radius of the cone and cylinder $r=\frac{4.2}{2}=2.1m$

Height of the cone $h_1=2.8m$

Height of the cylinder $h_2=4m$

Capacity of tent $=$ Volume of cone$+$ volume of cylinder

                           $=\frac{1}{3}\pi r^2{h}_1+\pi r^2{h}_2$

                          $=\frac{1}{3}\times \frac{22}{7}\times 2.1\times 2.1\times 2.8+\frac{22}{7}\times 2.1\times 2.1\times 4=68.376m^3$

$l=\sqrt{h_1{}^2+r^2}=\sqrt{{2.1}^2+{2.8}^2}=3.5m$

Canvas used for tent$=$ C.S.A of cone $+$ C.S.A of cylinder

                                 $=\pi rl+2\pi rh$

                                 $=\frac{22}{7}\times 2.1\times 3.5+2\times \frac{22}{7}\times 2.1\times 4=75.9m^2$

Cost of canvas$=75.9\times 100=Rs.7590$