David's decision on the electronics to purchase represents opportunity cost.
The decision to hire another economist is marginal analysis.
Ana's decision on how to use her time involves opportunity cost.
<h3>What is opportunity cost?</h3>
Opportunity cost of the next best option forgone when one alternative is chosen over other alternatives. When an economic agent chooses one option, he would not be able to choose another option.
<h3>What is marginal analysis?</h3>
Marginal analysis involves comparing the marginal cost or / and the marginal benefit of a decision.
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