2. In a paint manufacturing unit, each type of paint is to be ground to a specified degree of fineness. The manufacturer uses the same ball mill for a variety of paints and after completion of each batch, the mill has to be cleaned and the ball change properly made up. The changeover from one type of paint to another is estimated to cost Rs. 800 per batch. The annual sales of a particular grade of paint are 30000 litres and the inventory carrying cost in Rs. 10 per litre. Given that the rate of production is 3 times the sales rate, determine the economic batch size.