Consider the transportation problem formulation and solution of the Metro Water District problem presented in Sec. 8.1 and 8.2. The numbers given in the parameter table are only estimates that may be somewhat inaccurate, so management now wishes to do some what-if analysis. Use the Excel Solver to generate the Sensitivity Report. Then use this report to address the following questions. (In each case, assume that the indicated change is the only change in the model.)
(a) Would the optimal solution in Table 8.23 remain optimal if the cost per acre foot of shipping Calorie River water to San Go were actually $200 rather than $230?
(b) Would this solution remain optimal if the cost per acre foot of shipping Sacron River water to Los Devils were actually $160 rather than $130?
(c) Must this solution remain optimal if the costs considered in parts (a) and (b) were simultaneously changed from their original values to $215 and $145, respectively?
(d) Suppose that the supply from the Sacron River and the demand at Hollyglass are decreased simultaneously by the same amount. Must the shadow prices for evaluating these changes remain valid if the decrease were 0.5 million acre feet?