2 .
A hollow cylindrical tube 20 cm long, is made of iron and its external and internal diameters are 8cm and 6 cm respectively. The volume of iron used in making the tube is:
4 .
A wire when bent in the form of an equilateral triangle encloses a region having area of 121$\sqrt 3$ $cm^2$. If the same wire is bent into the form of a circle, the area (in $cm^2$) enclosed by the wire is: