Directions (1 - 3): Purana and Naya two brand of mixer-grinder available in the market. Purana was introduced in 1990 and Naya was introduced in 1997. For both brands, 20% of the mixer-grinder bought in a particular year are disposed off as junk exactly two year later. It is known that 10 Purana mixer-grinder were disposed off in 1997. The following chart show the operation from 1995 to 2000, as at end of the year.