A deterministic model typically involves the use of an equation or a set of equations to describe, represent or model relationships between the various components of a system or problem. Sometimes, these components can be represented by variables, which can be defined mathematically. In this chapter, five different problem situations will be examined. These include determining the best correction tape, finding an optimal way to construct a car park, choosing the best cross-sectional shape for a drain, designing a covered walkway, and designing a new dartboard game. In each case, a detailed treatment and discussion on each activity will be provided.