3. Five projects are being evaluated over a 3-year planning horizon. The following table gives the expected returns for each project and the associated yearly expenditures: Project Expenditures ($ million)/year 1 2 3 Returns ($ million) 1 5 20 2 3 4 5 4 3 7 8 1 7 9 4 6 8 10 2 1 10 40 20 15 30 Available funds ($ million) 25 25 25 (i) (10 points) Formulate an IP problem to determine which projects should be selected over the 3-year horizon. (Use suitable binary indicator variables). (ii) (5 points) Suppose now that we have the additional condition that EITHER project 1 OR project 2 (not both) must be selected. How should the IP problem be modi- fied? What new constraint(s) must be added. (iii) (5 points) Now suppose we have another additional condition: at least two of projects 3, 4, and 5 must be chosen. How should the IP problem be modified now? What new constraint(s) must be added. (iv) (5 points) Finally, we have this condition: EITHER the constraint you wrote in part (ii), OR the constraint you wrote in part (iii) must be implemented. How would you modify the IP problem? What new constraint(s) must be added