In recent years, mathematical ideas have been extensively used in various areas of real life problems. Operations research is the representation of real life (day to day) problems as a mathematical formulated problems aiming at solving such problems and to get an optimal solution to such problems. While making use of the techniques of operations research, a mathematical model of the problem is formulated. This model is a simplified version of the real life problem which is solved and tested for optimality. During the last six decades many mathematical tools have been developed for operations research. In 1957, two mathematician Margon R. Walker and James E. Kelly [33] developed a project management method called critical path method (CPM). CPM is an algorithm for scheduling a set of project activities and critical path method is one of the network management techniques. It is a method used to make decisions in analyzing, planning, scheduling and monitoring various kinds of projects in various fields.