Deriving the Solution from the Model: This phase is devoted to the computation of those value of decision variables that maximize or minimize the objective function. Such solution is called an optimal solution.

Validity of the Model: The model should be validated to measure its accuracy . that is in order for a model to be useful, the degree to which it actually represents the systems or problem being modelled must be established. A models valid or accurate if.

a. It contains all the objective constraints and decision variables relevant to the problem.

b. The objectives constraints and decision variable included in the model are all relevant to or actually part of the problem and

c. The functional relationship are valid.