3. A regular square pyramid has side of its base 20 cm and height 45 cm is melted and recast into regular triangular pyramids of equilateral base of side 10 cm and height 10?3 cm. What are the total numbers of regular triangular pyramid?
5. Three toys are in a shape of cylinder, hemisphere and cone. The three toys have same base. Height of each toy is 2?2 cm. What is the ratio of the total surface areas of cylinder, hemisphere and cone respectively?