AP Microeconomics Quiz: Cost Benefit Analysis

What this quiz covers

This quiz focuses on Cost Benefit Analysis, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Microeconomics.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. an implicit cost that should be added to the additional investment required for the launch.
2. a sunk cost that is irrelevant to the decision of whether to launch the product. (correct answer)
3. a marginal cost that must be weighed against the marginal benefit of the first unit sold.
4. an opportunity cost of not hiring a different, potentially better, consulting firm.

Explanation: 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.

Question 2

1. Project A, because its net benefit of $2,000$ is greater than Project B's net benefit of $1,000$. (correct answer)
2. Project B, because its total benefit of $15,000$ is higher than Project A's total benefit of $10,000$.
3. Project A, because its costs are significantly lower, representing less financial risk for the firm.
4. Neither project, because the opportunity cost of choosing one is the net benefit of the other.

Explanation: Rational decision-making aims to maximize net benefits (Total Benefits - Total Costs). The net benefit of Project A is $10,000 - 8,000 = 2,000$. The net benefit of Project B is $15,000 - 14,000 = 1,000$. Since Project A has the higher net benefit, it is the optimal choice.

Question 3

1. Go to the game, because she already spent $50$ on the ticket and should not waste it.
2. Go to the party, because its value ($60$) is greater than the enjoyment from the game ($40$). (correct answer)
3. Go to the game, because the total value ($40$ enjoyment + $50$ ticket) is greater than the party's value.
4. Go to the party, because the net benefit is $10$ ($60$ value - $50$ ticket cost).

Explanation: 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.

Question 4

1. Stop after 2 routes
2. Stop after 4 routes
3. Stop after 5 routes
4. Stop after 3 routes (correct answer)
5. Stop after 1 route

Explanation: 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.

Question 5

1. Perform 4 inspections
2. Perform 2 inspections
3. Perform 5 inspections
4. Perform 3 inspections (correct answer)
5. Perform 1 inspection

Explanation: 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 inspection, where MB of $260 is less than MC of $360. Thus, the optimal is three inspections, as each of the first three has MB exceeding or equaling MC, maximizing net benefits. A common mistake is calculating total benefits versus total costs instead of using marginal comparisons for incremental choices. 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.

Question 6

1. A government increases taxes on all citizens to pay for a new highway system, which improves transportation for everyone.
2. A government prints more money to finance its spending, leading to an increase in the overall price level (inflation).
3. A government chooses to fund a universal healthcare program, and as a result, it cannot fund a planned expansion of the military. (correct answer)
4. A government receives foreign aid, which it uses to build new schools and hospitals in underserved areas of the country.

Explanation: 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.

Question 7

1. Fund 4 sessions
2. Fund 2 sessions
3. Fund 5 sessions
4. Fund 1 session
5. Fund 3 sessions (correct answer)

Explanation: 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.

Question 8

1. Yes, because the homeowner should continue as long as marginal benefit is positive
2. No, because the marginal cost of the 3rd upgrade step exceeds its marginal benefit (correct answer)
3. Yes, because the average marginal benefit through 3 steps exceeds the marginal cost of the 3rd step
4. No, because the homeowner should stop at the step with the highest marginal benefit (the 1st step)
5. Yes, because total benefits must be compared to total costs rather than marginal values

Explanation: 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 third upgrade, MB of $320 is less than MC of $330, indicating the flip. Therefore, the homeowner should not undertake the third, as it would result in a net loss despite positive MB. A common mistake is averaging benefits over all units instead of evaluating each marginally. 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.

Question 9

1. greater than $3,500$, the total amount spent on repairs.
2. greater than $3,000$, the cost of a replacement car. (correct answer)
3. greater than $2,500$, the cost of the new transmission.
4. greater than $1,000$, the amount already spent on repairs.

Explanation: The $1,000$ already spent is a sunk cost and irrelevant to the decision. The owner must choose between: (1) spending $2,500$ to repair the current car, or (2) spending $3,000$ to buy a replacement. The repair is rational only if the repaired car's value exceeds the cost of the best alternative, which is $3,000$ for the replacement car.

Question 10

1. $40$, which is the explicit cost of the concert ticket.
2. $60$, which is the value of the income forgone from not working.
3. $100$, which includes both the explicit cost of the ticket and the implicit cost of forgone earnings. (correct answer)
4. $20$, which is the difference between the income forgone and the cost of the ticket.

Explanation: 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 $40 + 60 = 100$.

Question 11

1. The $120,000$ forgone salary plus the $50,000$ from savings, for a total of $170,000$.
2. The $120,000$ forgone salary plus the $2,000$ in forgone interest, for a total of $122,000$. (correct answer)
3. Only the $120,000$ forgone salary, as the savings were her own money.
4. Only the $2,000$ in forgone interest, as this is the only direct financial opportunity lost.

Explanation: 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 $120,000 + 2,000 = 122,000$.

Question 12

1. the explicit costs of the action are less than the explicit benefits.
2. the total economic costs, including opportunity costs, are less than the total benefits. (correct answer)
3. the action generates positive total revenue, even if it results in an economic loss.
4. the action has no associated implicit costs, making it cheaper than other alternatives.

Explanation: 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.

Question 13

1. the wages a student could have earned from a full-time job.
2. the money spent on tuition, fees, and required textbooks.
3. the money spent on room and board for housing and food. (correct answer)
4. the interest that could have been earned on money spent for tuition.

Explanation: 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.

Question 14

1. Staff 5 additional shifts
2. Staff 2 additional shifts (correct answer)
3. Staff 3 additional shifts
4. Staff 1 additional shift
5. Staff 4 additional shifts

Explanation: 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.

Question 15

1. Yes, because total marginal benefits are still positive
2. No, because the marginal cost of the 4th hour exceeds its marginal benefit (correct answer)
3. Yes, because the 3rd hour had $\text{MB}=\text{MC}$ so the shop should continue past it
4. No, because the shop should stop when $\text{MB}=\text{MC}$ occurs (at the 3rd hour)
5. Yes, because the marginal benefit is greater than the average marginal cost through 4 hours

Explanation: 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.

Question 16

1. Complete 2 practice exams
2. Complete 5 practice exams
3. Complete 3 practice exams (correct answer)
4. Complete 1 practice exam
5. Complete 4 practice exams

Explanation: 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.

Question 17

1. positive economic profit and positive accounting profit.
2. negative economic profit but positive accounting profit. (correct answer)
3. positive economic profit but negative accounting profit.
4. negative economic profit and negative accounting profit.

Explanation: 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.

Question 18

1. $200,000$
2. $80,000$
3. $10,000$ (correct answer)
4. -$10,000$

Explanation: 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.

Question 19

1. The owner should not stay open, because the total monthly costs exceed the extra revenue.
2. The owner should stay open, because the additional revenue of $200$ exceeds the additional costs of $100$. (correct answer)
3. The owner should not stay open, because the additional revenue of $200$ is less than the total cost of $3,100$.
4. The owner should consider the rent as a marginal cost of staying open the extra hour.

Explanation: 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.

Question 20

1. The $2 million construction cost of the pool.
2. The $2.2 million in benefits from the forgone park upgrades. (correct answer)
3. The $500,000$ net benefit of the swimming pool project.
4. The $200,000$ net benefit of the park upgrade project.

Explanation: 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.