b. A company is planning to determine its product mix out three different products: P1, P2, P3. The monthly sale of the product P, is limited to a maximum of 500 units. For every two units of P2 produced, there will be one unit of by product which can be sold at the rate of Rs.20/unit. The highest monthly demand for this by product is 200 units. The contributions/unit of the product P1, P2, P3 are Rs.50, Rs. 70 and Rs.60 respectively. The processing requirement for three products are shown in table below: Process Hours/unit Available hours PI P2 P3 3 5 2 1000 II W 700 III W 1300 Formulate a linear programming model of this problem to find the optimum product mix such that the total contribution is maximized. (10 Marks)