A self help group wants to manufacture joker’s caps (conical caps) of 3cm radius and 4cm height. If the available colour paper sheet is 1000 cm2, then how many caps can be manufactured from that paper sheet?

The radius of conical cap (r) = 3cm : height (h) = 4cm

Slant height of conical cap (l) $=\sqrt{r^2+h^2}=\sqrt{3^2+4^2}=5cm$

  L.S.A of conical cap$=\pi rl=\frac{22}{7}\times 3\times 5=\frac{330}{7}c{m}^2$

 The colour paper sheet required to make one cap$=\frac{330}{7}c{m}^2$

   Available colour paper sheet = 1000 cm²

  $\therefore$ Number of caps manufactured from the paper sheet = integral part of $\frac{1000}{\left(\frac{330}{7}\right)}=21$