Marginal analysis entails evaluating the additional benefits to be derived from an activity to additional cost. It involves a cost-benefit evaluation of the decision.
In the question, the additional income is large amount of income while the additional cost is very small(it requires little staff and little damage). So, the benefits outweigh the cost.
So the university’s decision to rent its campus to a conference group is clearly based of marginal analysis.
Software system modeling is a technique to deal with the complexity inherent in these systems. The use of models helps the software engineer to "visualize" the system to be built. In addition, models of a higher level of abstraction can be used for communication with the customer. Finally, the modeling tools and those of Automated Software Engineering. They can help verify the correctness of the model.
