Cost-Benefit Analysis - AP Microeconomics

A high school student can work a 4-hour shift at a local coffee shop earning $15$ per hour, or they can attend a concert. The ticket for the concert costs $40$ . What is the total opportunity cost for this student to attend the concert?
Answer: $100$ , which includes both the explicit cost of the ticket and the implicit cost of forgone earnings. Opportunity cost is the value of the next-best alternative forgone. It includes both explicit costs (the ticket price of $40$ ) and implicit costs (the $15/hour * 4 hours = 60$ in forgone wages). The total opportunity cost is the sum of these, which is $40 + 60 = 100$ .
The opportunity cost of attending a four-year college includes all of the following EXCEPT
Answer: the money spent on room and board for housing and food. Opportunity cost includes costs that are a direct result of the decision. A student needs to pay for housing and food whether they attend college or not. Therefore, room and board are not typically counted as an opportunity cost of college, unless the cost is significantly higher at college than it would be otherwise. Tuition, fees, forgone wages, and forgone interest are all direct opportunity costs.
The primary goal of cost-benefit analysis in public policy decisions is to
Answer: select projects where the total social benefits are greater than the total social costs, thereby promoting allocative efficiency. Cost-benefit analysis is a systematic process for calculating and comparing the benefits and costs of a project, decision, or government policy. Its purpose is to determine if a decision is sensible in terms of its net benefit to society, which aligns with the goal of allocative efficiency.
A delivery company is deciding how many additional delivery routes to add on Saturdays (each unit is one route). According to the marginal benefit and marginal cost data in the table, at which quantity should the company stop adding routes? <table> <tr><th>Routes (Q)</th><th>MB, $</th><th>MC, $</th></tr> <tr><td>1</td><td>900</td><td>500</td></tr> <tr><td>2</td><td>800</td><td>600</td></tr> <tr><td>3</td><td>700</td><td>700</td></tr> <tr><td>4</td><td>600</td><td>800</td></tr> <tr><td>5</td><td>500</td><td>900</td></tr> </table>
Answer: Stop after 3 routes Marginal cost-benefit analysis is a key skill in microeconomics for making optimal decisions about resource allocation. Marginal benefit (MB) is the additional benefit from one more unit, while marginal cost (MC) is the additional cost; the decision rule is to proceed with additional units as long as MB ≥ MC and stop at the first unit where MB < MC. In this data, the inequality flips at the fourth route, where MB of $600 is less than MC of $800. Therefore, the company should stop after three routes, as that is the last where MB ≥ MC, optimizing profits. A common mistake is using average costs or benefits instead of marginals, which can mislead on incremental value. To apply this transferable strategy, always compare MB and MC unit-by-unit starting from the first. Additionally, ignore sunk costs and focus only on future benefits and costs; on graphs, look for where the MB and MC curves intersect to find the optimal quantity.
A farmer has total revenue of $200,000$ from selling crops. The farmer's explicit costs for seed, fertilizer, and equipment rental total $120,000$ . If the farmer had not worked on the farm, she could have earned $70,000$ as a manager at a local store. The farmer's economic profit is
Answer: $10,000$ Economic profit is total revenue minus all costs (explicit and implicit). Explicit costs are $120,000$ . The implicit cost is the forgone salary of $70,000$ . Economic Profit = $200,000 (Total Revenue) - $120,000$ (Explicit Costs) - $70,000$ (Implicit Costs) = $10,000.
A student is deciding how many practice exams to complete before an AP Microeconomics test (each unit is one practice exam). According to the marginal benefit and marginal cost data in the table, what is the optimal number of practice exams to complete? <table> <tr><th>Practice exams (Q)</th><th>MB (points of expected score gain)</th><th>MC (hours of study time)</th></tr> <tr><td>1</td><td>12</td><td>3</td></tr> <tr><td>2</td><td>9</td><td>4</td></tr> <tr><td>3</td><td>7</td><td>5</td></tr> <tr><td>4</td><td>5</td><td>6</td></tr> <tr><td>5</td><td>4</td><td>7</td></tr> </table>
Answer: Complete 3 practice exams Marginal cost-benefit analysis is a key skill in microeconomics for making optimal decisions about resource allocation. Marginal benefit (MB) is the additional benefit from one more unit, while marginal cost (MC) is the additional cost; the decision rule is to proceed with additional units as long as MB ≥ MC and stop at the first unit where MB < MC. In this data, the inequality flips at the fourth exam, where MB of 5 points is less than MC of 6 hours. Therefore, the optimal is three exams, as the first three satisfy MB ≥ MC, balancing score gains against time costs. A common mistake is comparing totals rather than marginals, which can lead to over- or under-estimating the best quantity. To apply this transferable strategy, always compare MB and MC unit-by-unit starting from the first. Additionally, ignore sunk costs and focus only on future benefits and costs; on graphs, look for where the MB and MC curves intersect to find the optimal quantity.
Explicit costs of production are best characterized as
Answer: payments made to factors of production that the firm does not own. Explicit costs involve direct monetary payments to others for resources. This includes wages paid to labor, rent for land or buildings, and payments for raw materials—all of which are factors of production the firm hires or buys from others.
If a firm's total revenue covers its explicit costs but not the full sum of its explicit and implicit costs, the firm is earning
Answer: negative economic profit but positive accounting profit. If total revenue exceeds explicit costs, accounting profit (TR - Explicit Costs) is positive. However, if total revenue is less than the sum of explicit and implicit costs, economic profit (TR - Explicit Costs - Implicit Costs) is negative. This situation describes a firm that is profitable by accounting standards but is underperforming relative to its opportunity cost.
An entrepreneur quits her job as a software engineer, where she was earning an annual salary of $120,000$ , to start her own company. To fund the business, she uses $50,000$ from her savings account, which had been earning 4% annual interest. Which of the following represents the total implicit costs of her decision for the first year?
Answer: The $120,000$ forgone salary plus the $2,000$ in forgone interest, for a total of $122,000$ . Implicit costs are the opportunity costs of using resources the entrepreneur already owns, rather than paying for them. This includes the $120,000$ salary she gave up and the interest she could have earned on her savings ( $50,000 * 0.04 = 2,000$ ). The total implicit cost is $120,000 + 2,000 = 122,000$ .
A firm's implicit costs are also known as
Answer: opportunity costs of using the firm's own resources. Implicit costs represent the income or value forgone when a firm uses its own resources (like the owner's time or capital) for one purpose rather than another. This is the definition of opportunity cost applied to the resources a firm already owns.
When a firm is earning zero economic profit, it implies that
Answer: the firm's total revenue is equal to the sum of its explicit costs and implicit costs. Zero economic profit means that total revenue is exactly covering all costs, including both explicit (out-of-pocket) costs and implicit (opportunity) costs. This is the long-run equilibrium condition in perfect competition and means the firm is earning a normal rate of return.
Which of the following scenarios best illustrates the concept of opportunity cost for a government?
Answer: A government chooses to fund a universal healthcare program, and as a result, it cannot fund a planned expansion of the military. Opportunity cost is the value of the next-best alternative forgone when a choice is made. By choosing to spend its limited budget on healthcare, the government forgoes the opportunity to spend that money on military expansion. This trade-off is a direct example of opportunity cost.
Assume Sarah has a non-refundable, non-transferable ticket to a baseball game that she bought for $50$ . On the day of the game, her friend invites her to a party. Sarah values attending the party at $60$ . If she goes to the game, she will get $40$ of enjoyment. What is Sarah's best course of action and why?
Answer: Go to the party, because its value ( $60$ ) is greater than the enjoyment from the game ( $40$ ). The $50$ cost of the ticket is a sunk cost and should not influence the decision. The decision should be based on comparing the benefits of the available options. The benefit of the party ( $60$ ) is greater than the benefit of the game ( $40$ ). Therefore, the rational choice is to go to the party.
A university is deciding how many additional tutoring sessions to fund for an introductory economics course (each unit is one session). According to the marginal benefit and marginal cost data in the table, what is the optimal number of sessions to fund? <table> <tr><th>Tutoring sessions (Q)</th><th>MB, $</th><th>MC, $</th></tr> <tr><td>1</td><td>1,200</td><td>400</td></tr> <tr><td>2</td><td>1,000</td><td>600</td></tr> <tr><td>3</td><td>800</td><td>750</td></tr> <tr><td>4</td><td>650</td><td>900</td></tr> <tr><td>5</td><td>500</td><td>1,050</td></tr> </table>
Answer: Fund 3 sessions Marginal cost-benefit analysis is a key skill in microeconomics for making optimal decisions about resource allocation. Marginal benefit (MB) is the additional benefit from one more unit, while marginal cost (MC) is the additional cost; the decision rule is to proceed with additional units as long as MB ≥ MC and stop at the first unit where MB < MC. In this data, the inequality flips at the fourth session, where MB of $650 falls below MC of $900. This justifies funding three sessions, as each of the first three has MB exceeding MC, providing the greatest net value to students. A common mistake is focusing on total benefits without subtracting total costs, but marginal analysis ensures efficient stopping points. To apply this transferable strategy, always compare MB and MC unit-by-unit starting from the first. Additionally, ignore sunk costs and focus only on future benefits and costs; on graphs, look for where the MB and MC curves intersect to find the optimal quantity.
A coffee shop is considering extending its hours by adding one more hour each night (each "unit" is one added hour per night for the month). According to the marginal benefit and marginal cost data in the table, should the shop add the 4th hour? <table> <tr><th>Added hour (Q)</th><th>MB from added hour, $</th><th>MC of added hour, $</th></tr> <tr><td>1</td><td>220</td><td>120</td></tr> <tr><td>2</td><td>180</td><td>140</td></tr> <tr><td>3</td><td>150</td><td>150</td></tr> <tr><td>4</td><td>120</td><td>170</td></tr> <tr><td>5</td><td>90</td><td>190</td></tr> </table>
Answer: No, because the marginal cost of the 4th hour exceeds its marginal benefit Marginal cost-benefit analysis is a key skill in microeconomics for making optimal decisions about resource allocation. Marginal benefit (MB) is the additional benefit from one more unit, while marginal cost (MC) is the additional cost; the decision rule is to proceed with additional units as long as MB ≥ MC and stop at the first unit where MB < MC. In this data, for the fourth hour, MB of $120 is less than MC of $170, indicating the inequality has flipped. Therefore, the shop should not add the fourth hour, as it would reduce net benefits compared to stopping at three. A common mistake is focusing on total benefits being positive instead of comparing marginal values for each incremental decision. To apply this transferable strategy, always compare MB and MC unit-by-unit starting from the first. Additionally, ignore sunk costs and focus only on future benefits and costs; on graphs, look for where the MB and MC curves intersect to find the optimal quantity.
A city government is considering building a public swimming pool. The total cost of construction is estimated to be $2 million. The expected total benefit to the community over the pool's lifetime is valued at$ 2.5 million. An alternative use for the $2 million is to upgrade local parks, a project with an estimated total benefit of$ 2.2 million. What is the opportunity cost of building the swimming pool?
Answer: The $2.2 million in benefits from the forgone park upgrades. Opportunity cost is the value of the next-best alternative that must be forgone. In this case, the next-best alternative to building the pool is upgrading the parks. The value of that alternative is its total benefit of $2.2 million.
A rational agent will choose to take an action if
Answer: the total economic costs, including opportunity costs, are less than the total benefits. Rational decision-making requires considering all costs, both explicit and implicit (which together make up the total economic cost). An action is rational if the total benefits derived from it exceed the total economic costs incurred.
A restaurant owner is considering staying open for one extra hour at night. The total revenue from the extra hour is expected to be $200$ . The costs for that hour are $50$ for staff wages, $30$ for utilities, and $20$ for ingredients. The restaurant's monthly rent is $3,000$ . In this short-run decision, which of the following is correct?
Answer: The owner should stay open, because the additional revenue of $200$ exceeds the additional costs of $100$ . This decision should be made by comparing the marginal benefit ( $200$ in revenue) to the marginal cost. The marginal costs are the additional costs incurred for that specific hour: wages ( $50$ ) + utilities ( $30$ ) + ingredients ( $20$ ) = $100. The monthly rent is a fixed cost, not a marginal cost of staying open one more hour. Since MB ($ $200$ $) > MC ($ $100$ $), the owner should stay open.
A consultant charges $150,000$ for a market analysis report. A company pays this fee and receives the report. After reviewing the report, the company must decide whether to launch a new product, which requires an additional investment of $500,000$ . In making the decision to launch the new product, the $150,000$ fee for the report should be regarded as
Answer: a sunk cost that is irrelevant to the decision of whether to launch the product. A sunk cost is a cost that has already been incurred and cannot be recovered. Rational decision-making should ignore sunk costs and focus only on future costs and benefits. The $150,000$ has been paid regardless of the future decision, so it is irrelevant to the launch choice.
A city parks department is deciding how many additional weekend lifeguard shifts to staff at a public beach this month. The department has already spent $2,000 on training equipment (a sunk cost). According to the marginal benefit and marginal cost data in the table, what is the optimal number of lifeguard shifts to staff? <table> <tr><th>Additional shifts (Q)</th><th>Marginal Benefit (MB), $</th><th>Marginal Cost (MC), $</th></tr> <tr><td>1</td><td>900</td><td>400</td></tr> <tr><td>2</td><td>700</td><td>500</td></tr> <tr><td>3</td><td>550</td><td>600</td></tr> <tr><td>4</td><td>450</td><td>700</td></tr> <tr><td>5</td><td>350</td><td>800</td></tr> </table>
Answer: Staff 2 additional shifts Marginal cost-benefit analysis is a key skill in microeconomics for making optimal decisions about resource allocation. Marginal benefit (MB) is the additional benefit from one more unit, while marginal cost (MC) is the additional cost; the decision rule is to proceed with additional units as long as MB ≥ MC and stop at the first unit where MB < MC. In this data, the inequality flips at the third shift, where MB of $550 falls below MC of $600. Thus, the optimal number is 2 shifts, as both the first and second have MB exceeding MC, adding net value, but the third does not. A common mistake is including sunk costs like the $2,000 training in the decision, but these should be ignored since they are already spent. To apply this transferable strategy, always compare MB and MC unit-by-unit starting from the first. Additionally, ignore sunk costs and focus only on future benefits and costs; on graphs, look for where the MB and MC curves intersect to find the optimal quantity.

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