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√3cm2. If the same wire is bent into the form of a circle, the area (in cm2) enclosed by the wire is: