Medium LSAT Must Be True Questions With Answers Practice Questions

Medium LSAT Must Be True Questions With Answers Practice Questions

Logical reasoning accounts for approximately 50% of your total score on the LSAT Prep curriculum, making the ability to identify valid inferences a non-negotiable skill for law school applicants. Must Be True questions require you to select an answer choice that is 100% supported by the provided stimulus, leaving no room for outside assumptions or hypothetical possibilities. These questions test your ability to distinguish between what is likely and what is logically certain. By engaging with Medium LSAT Must Be True Questions With Answers, you can bridge the gap between basic logic and the complex conditional reasoning required for the highest percentiles.

Concept Explanation

LSAT Must Be True questions are logical inference tasks where the correct answer choice is a statement that is strictly proven by the information presented in the stimulus. Unlike other question types that ask you to strengthen or weaken an argument, these questions treat the stimulus as a set of facts that are beyond dispute. The correct answer is often a paraphrase of one of the premises or a logical deduction resulting from the combination of two or more premises. To succeed, you must avoid "could be true" answers—statements that are plausible but not guaranteed—and "new information" answers that introduce concepts not discussed in the text. Common logical structures found in these questions include conditional statements (if-then), causal relationships, and quantifier-based logic (some, most, all).

Standard techniques for solving these include:

• Conditional Mapping: Converting "if-then" statements into symbolic logic to track transitive properties.
• Fact Inventory: Treating the stimulus as a closed universe where only the provided facts exist.
• The Umbrella Test: Asking yourself, "If the stimulus is true, can the answer choice be false?" If it can be false, it is not the correct answer.

Solved Examples

Example 1: Conditional Chains

Stimulus: If a legal system is to be considered just, it must protect the rights of the minority. Any system that protects the rights of the minority inevitably faces occasional public backlash. The country of Valoria has a legal system that has never faced public backlash.

1. Identify the conditional statements: $\text{Just} \rightarrow \text{Minority Rights}$ and $\text{Minority Rights} \rightarrow \text{Backlash}$.
2. Chain them together: $\text{Just} \rightarrow \text{Minority Rights} \rightarrow \text{Backlash}$.
3. Apply the contrapositive to the fact about Valoria: Valoria has $eg \text{Backlash}$.
4. Work backward: $eg \text{Backlash} \rightarrow eg \text{Minority Rights} \rightarrow eg \text{Just}$.
5. Conclusion: Valoria's legal system is not considered just.

Example 2: Quantifiers (Most and Some)

Stimulus: Most successful litigators are highly competitive. Some highly competitive individuals suffer from chronic stress. No one who suffers from chronic stress can maintain a perfect work-life balance.

1. Break down the groups: Most (more than 50%) of Litigators = Competitive. Some Competitive = Stress. Stress $\rightarrow$ No Balance.
2. Look for intersections: Since "some" competitive people have stress, and all stress people have no balance, we can conclude that some competitive people have no balance.
3. Check the litigator connection: We cannot conclude most litigators have stress, nor that any specific litigator lacks balance, because the "some" might not overlap with the "most."
4. Conclusion: At least some highly competitive individuals cannot maintain a perfect work-life balance.

Example 3: Causal vs. Conditional

Stimulus: The recent increase in city property taxes has led to a decrease in small business expansions. Whenever small business expansion decreases, the local unemployment rate rises.

1. Map the causal/conditional link: $\text{Tax Increase} \rightarrow \text{Expansion Decrease} \rightarrow \text{Unemployment Rise}$.
2. Analyze the scope: The tax increase triggered the chain.
3. Evaluate the outcome: The unemployment rate must have risen following the tax increase.
4. Conclusion: The recent increase in city property taxes was followed by a rise in the local unemployment rate.

Practice Questions

1. All modern sculptures in the gallery are made of bronze. Some of the bronze sculptures in the gallery were created by local artists. No local artist uses recycled materials in their bronze work.

2. If a corporation prioritizes short-term profits over long-term sustainability, it will eventually lose its market share. The Megacorp Inc. has maintained or increased its market share for the past thirty years. Only corporations that invest heavily in R&D can achieve long-term sustainability.

3. Most students who study for more than twenty hours a week perform well on the exam. Every student who performs well on the exam receives a certificate of merit. Some students who receive a certificate of merit are also offered internships.

4. In a study of 500 patients, those who took Medication X showed a 20% faster recovery rate than those who took a placebo. However, 15% of the patients who took Medication X reported mild nausea, whereas only 2% of the placebo group reported similar symptoms.

5. No professional athlete who consumes a high-sugar diet can maintain peak cardiovascular performance. Some marathon runners consume high-sugar diets. All individuals who maintain peak cardiovascular performance have a resting heart rate below 60 beats per minute.

6. If the temperature drops below freezing, the lake will ice over. If the lake ices over, the local fishing competition will be canceled. The local fishing competition was not canceled this year.

7. Every member of the board of directors owns stock in the company. Some employees who own stock in the company are also members of the union. No member of the union is allowed to sit on the board of directors.

8. Research indicates that most people who drink green tea regularly have lower blood pressure than those who do not. High blood pressure is a leading cause of heart disease. However, drinking more than five cups of green tea a day can lead to insomnia.

Answers & Explanations

1. Answer: Some bronze sculptures in the gallery are not made of recycled materials.
Explanation: We know some bronze sculptures are by local artists. We also know local artists do not use recycled materials in their bronze work. Therefore, the specific bronze sculptures made by local artists are not made of recycled materials. This is a classic "some" intersection logic similar to what you might find in Hard GRE Reading Practice Test Practice Questions.

2. Answer: Megacorp Inc. does not prioritize short-term profits over long-term sustainability.
Explanation: The stimulus gives the condition $\text{Short-term} \rightarrow \text{Lose Share}$. The contrapositive is $\text{Maintain Share} \rightarrow eg \text{Short-term}$. Since Megacorp maintained its share, it must not have prioritized short-term profits.

3. Answer: At least some students who study for more than twenty hours a week receive a certificate of merit.
Explanation: Most ($>50\%$) who study 20+ hours perform well. Everyone who performs well gets a certificate. Therefore, that "most" group must all have certificates. This follows the transitive property of quantifiers.

4. Answer: Some patients who recovered faster after taking Medication X experienced mild nausea.
Explanation: While we don't know the exact overlap, the stimulus establishes that the group taking Medication X (which recovered faster) also had a 15% incidence of nausea. It is mathematically certain that some within the Medication X group fall into both categories.

5. Answer: Some marathon runners do not have a resting heart rate below 60 beats per minute.
Explanation: Some marathon runners have high-sugar diets. High-sugar diets mean they cannot maintain peak performance. If they don't have peak performance, we cannot conclude they have a low heart rate based on the stimulus (which only links peak performance to low heart rate). However, the contrapositive of the last statement is $eg \text{Low Heart Rate} \rightarrow eg \text{Peak Performance}$. This actually means those without peak performance *could* have high heart rates, but the direct inference is that some marathon runners (the high-sugar ones) lack the requirement for the guaranteed low heart rate.

6. Answer: The temperature did not drop below freezing.
Explanation: This uses multiple contrapositives. $\text{Not Canceled} \rightarrow \text{Not Iced Over} \rightarrow \text{Not Below Freezing}$. Each step is logically sound based on the initial "if-then" statements.

7. Answer: Some employees who own stock in the company are not on the board of directors.
Explanation: Some employees who own stock are union members. Union members cannot be on the board. Therefore, those specific employees (the union ones) cannot be on the board.

8. Answer: Drinking green tea regularly does not guarantee that one will never develop heart disease.
Explanation: The stimulus says green tea drinkers have *lower* blood pressure and that high blood pressure is a *leading* cause. It does not say it is the *only* cause, nor that green tea eliminates the risk entirely. This avoids the "absolute" trap.

Frequently Asked Questions

How do Must Be True questions differ from Most Strongly Supported questions?

Must Be True questions require a 100% logical guarantee based on the text, whereas Most Strongly Supported questions allow for a slightly lower threshold where the answer is highly probable but not necessarily certain. In Must Be True, any answer that could possibly be false is incorrect.

What is a "soft" Must Be True question?

A "soft" Must Be True question is another name for a Most Strongly Supported question, which often appears in the Logical Reasoning section of the LSAC official exams. These require you to find the choice that is best proven by the facts, even if it isn't a strict mathematical tautology.

Can I use outside knowledge for LSAT Must Be True questions?

No, you must never use outside information or general knowledge to answer Must Be True questions. The answer must be derived solely from the information provided in the stimulus, even if the stimulus contradicts real-world facts.

What are common trap answers in these questions?

Common traps include "Could Be True" answers, which are possible but not certain, and "Exaggerated" answers, which take a "some" or "most" statement from the stimulus and turn it into an "all" statement in the choice. Using an AI Exam Simulator can help you identify these patterns through repeated exposure.

Why is the contrapositive important for Must Be True questions?

The contrapositive is the only logically equivalent form of a conditional statement, making it a frequent source for correct answers. If a stimulus says $A \rightarrow B$, the LSAT will often provide $eg B \rightarrow eg A$ as the correct answer choice to test your ability to flip and negate the logic.

Is it helpful to diagram every Must Be True question?

Diagramming is most helpful when the stimulus contains multiple conditional statements that can be linked into a chain. For questions involving causal relationships or simple percentages, mental mapping or shorthand notes are often more efficient than full formal logic diagrams.