If the marginal benefits of studying for an exam are to academic performance as the marginal costs are to time spent studying, what would the optimal decision be when the marginal benefits start to equal the marginal costs?

When we talk about marginal benefits and marginal costs, we are looking at the additional advantages and disadvantages of studying more. The marginal benefits, like better grades or understanding the material, are what you gain from studying. The marginal costs are the time and effort you spend studying, which could have been used for other activities. The optimal decision occurs when the benefits of studying are equal to the costs; this is the point where you are getting the most value for the time you invest. For example, if studying for one more hour gives you a slight boost in your grade but also means you miss out on hanging out with friends, you should stop studying when those benefits and costs balance out.