PSI believes that the amounts of generating capacity needed during the next five years shown in Table Q4b1. The company has a choice of building (and then operating) power plants with the specifications shown in Table Q4b2. Formulate an IP to minimize the total costs of meeting the generating capacity requirements of the next five years. (10 marks) Year 1 2 3 4 5 Table Q4b1 Generating capacity (Million kwh) 80 100 120 140 160 Plant 1 Table Q4b2 Generating capacity Construction cost Annual operation (Million kwh) ($ millions) cost ($ millions) 70 20 1.5 50 16 0.8 60 1.3 40 14 0.6 2 3 4 18