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124   CHAPTER 3 LINEAR PROGRAMMING: SENSITIVITY ANALYSIS AND INTERPRETATION OF SOLUTION


                                    leads to the formulation:
                                                        Max  40F þ 30S
                                                        s:t
                                                             2      1
                                                              / F þ / S   20 Material 1
                                                               5     2
                                                                   1
                                                                    / S   5  Material 2
                                                                     2
                                                              3    3
                                                              / F þ / S   21 Material 3
                                                                     10
                                                               5
                                                               F; S   0
                                Use the graphical sensitivity analysis approach to determine the range of optimality for
                                the objective function coefficients.
                                2   For Problem 1 use the graphical sensitivity approach to determine what happens if an
                                    additional three kilos of material 3 become available. What is the corresponding dual price
                                    for the constraint?
                                3   Consider the following linear programme:
                                                              Max  2x 1 þ 3x 2
                                                              s:t
                                                                    x 1 þ x 2   10
                                                                   2x 1 þ x 2   4
                                                                    x 1 þ 3x 2   24
                                                                   2x 1 þ x 2   16
                                                                     x 1 ; x 2   0

                                    a. Solve this problem using the graphical solution procedure.
                                    b. Calculate the range of optimality for the objective function coefficient of x 1 .
                                    c. Calculate the range of optimality for the objective function coefficient of x 2 .
                                    d. Suppose the objective function coefficient of x 1 is increased from 2 to 2.5. What is the
                                      new optimal solution?
                                    e. Suppose the objective function coefficient of x 2 is decreased from 3 to 1. What is the
                                      new optimal solution?

                                4   Refer to Problem 3. Calculate the dual prices for constraints 1 and 2 and interpret them.
                                5   Consider the following linear programme:
                                                              Min  x 1 þ x 2
                                                              s:t
                                                                    x 1 þ 2x 2   7
                                                                   2x 1 þ x 2   5
                                                                    x 1 þ 6x 2   11
                                                                     x 1 ; x 2   0


                                    a. Solve this problem using the graphical solution procedure.
                                    b. Calculate the range of optimality for the objective function coefficient of x 1 .
                                    c. Calculate the range of optimality for the objective function coefficient of x 2 .
                                    d. Suppose the objective function coefficient of x 1 is increased to 1.5. Find the new optimal
                                      solution.
                                    e. Suppose the objective function coefficient of x 2 is decreased to one-third. Find the new
                                      optimal solution.

                                6   Refer to Problem 5. Calculate and interpret the dual prices for the constraints.





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