Maximum change in marginal Profit or Cost
Just as we did in studying the permissible ranges for changes in resources, we are also interested in studying the permissible ranges for changes in marginal profits (or costs). We have seen graphically that the objective function coefficients can change within limits without affecting the optimum values of the variables (the optimum value of Z will change, though).
In the present situation, as in the case of resource changes, the objective equation is never used as a pivot equation. Thus, any changes in the coefficients of the objective function will affect only the objective equation in the optimum tableau. This means that such changes can have the effect of making the solution non-optimal. Our goal is to determine the range of variation for the object coefficients (one at a time) for which the current optimum (solution) remains unchanged.