Final answer:
The power-sizing model is used to obtain a ballpark estimate, which is a rough initial approximation of costs or feasibilities in engineering projects.
Step-by-step explanation:
The power-sizing model in the field of engineering is a mathematical tool used to roughly estimate costs and feasibilities of different design approaches or technologies. When applying the power-sizing model, estimators usually seek ballpark figures for budgets, comparisons with other alternatives, or an initial assessment of a project's practicality.
Looking at prior examples and the question provided, the power-sizing model can be used to obtain a ballpark estimate (a), which serves as a preliminary approximation of the values involved. This technique draws on prior experience and sound physical reasoning to provide a rough idea of a quantity's value, much like the strategies used by physicist Enrico Fermi.