LSAT Logical Reasoning Practice Set 5 Practice Questions with Answers

Twenty-five questions typically comprise a single section of the LSAT Logical Reasoning exam, requiring students to analyze arguments within a strict 35-minute limit. This LSAT Logical Reasoning Practice Set 5 focuses on refining your ability to identify flaws, strengthen premises, and draw valid inferences under pressure. By engaging with these specific exercises, you develop the mental agility necessary to navigate the complex linguistic structures favored by the Law School Admission Council (LSAC).

Concept Explanation

LSAT Logical Reasoning is a standardized assessment of your ability to analyze, evaluate, and complete arguments by identifying the underlying relationships between premises and conclusions. At its core, this section tests formal logic, informal fallacies, and the ability to distinguish between necessary and sufficient conditions. Success requires a deep understanding of argument structure, which consists of a conclusion (the main point) and premises (the evidence supporting that point). Utilizing tools like an AI Question Generator can help you isolate these structures through targeted practice. Most questions fall into specific categories, such as Flaw, Strengthen/Weaken, Assumption, and Inference, each requiring a distinct strategic approach to isolate the correct answer choice among four attractive distractors.

Solved Examples

Review these worked examples to understand the step-by-step logic required for high-level reasoning.

1. Flaw in Reasoning: "Every student who studied for more than ten hours passed the exam. Since Sarah passed the exam, she must have studied for more than ten hours."
   1. Identify the formal logic: If Study > 10 hrs \u2192 Pass.
   2. Identify the conclusion: Sarah passed, therefore she studied > 10 hrs.
   3. Analyze the error: This is a Mistaken Reversal. The premise says studying is sufficient for passing, but it doesn't say it is necessary. Sarah could have passed for other reasons.
   4. Correct Flaw: The argument treats a condition that is sufficient for an outcome as if it were necessary for that outcome.
2. Strengthen the Argument: "A recent study shows that people who eat dark chocolate daily have lower blood pressure. Therefore, dark chocolate consumption directly improves cardiovascular health."
   1. Identify the conclusion: Dark chocolate causes improved health (causation).
   2. Identify the evidence: A correlation between chocolate and lower blood pressure.
   3. Find the gap: Correlation does not equal causation. Perhaps healthy people just happen to like chocolate.
   4. Strengthen: A study showing that when people who previously ate no chocolate began eating it daily, their blood pressure dropped significantly while other habits remained constant.
3. Necessary Assumption: "The city will not be able to build the new stadium unless it raises property taxes. Thus, the city will not build the stadium."
   1. Identify the logic: Build Stadium \u2192 Raise Taxes.
   2. Identify the conclusion: No Stadium.
   3. Find the missing link: The argument assumes the city will not raise property taxes.
   4. Test the assumption: If the city does raise taxes, the conclusion (no stadium) no longer follows. This confirms the assumption is necessary.

Practice Questions

Apply the techniques discussed above to the following LSAT Logical Reasoning Practice Set 5 questions. These range from basic conditional logic to complex causal reasoning.

1. Most successful entrepreneurs possess a high degree of risk tolerance. John is a successful entrepreneur. Therefore, John likely possesses a high degree of risk tolerance.

2. If the company's profits increase this quarter, the CEO will receive a bonus. The CEO did not receive a bonus. Therefore, the company's profits did not increase this quarter.

3. A nutritionist claims that drinking green tea reduces the risk of heart disease. To support this, she points to a study where green tea drinkers had 20% fewer heart attacks than non-drinkers. Which of the following, if true, most weakens the nutritionist's claim?

4. All mammals are warm-blooded. Some warm-blooded creatures live in the ocean. Therefore, some mammals live in the ocean. Is this argument valid?

5. The mayor argued that the new bike lanes have caused a decrease in traffic congestion because congestion has decreased since the lanes were installed. What is the primary flaw in the mayor's reasoning?

6. No one who is allergic to peanuts should eat this granola bar. Sarah is not allergic to peanuts. Therefore, Sarah should eat this granola bar. Identify the logical error.

7. To graduate with honors, a student must have a GPA of at least 3.8 and complete a senior thesis. Mark has a 3.9 GPA but did not complete a senior thesis. What can be concluded about Mark?

8. Many people believe that drinking coffee causes insomnia. However, a study found that people with insomnia tend to drink more coffee to stay alert during the day. This suggests that insomnia causes increased coffee consumption, rather than the other way around. Which technique is used here?

9. Any politician who supports the new tax bill is not a true fiscal conservative. Representative Smith supports the new tax bill. Therefore, Representative Smith is not a true fiscal conservative. What is the necessary assumption?

10. Every time the local sports team wins, the city's crime rate drops. Therefore, winning sports games leads to a safer city. How would you strengthen this causal claim?

Answers & Explanations

1. Answer: Valid Probabilistic Argument. The premise uses "most" (more than 50%), and the conclusion uses "likely." Since John is part of the group (entrepreneurs) where the majority have the trait, it is logically sound to say he likely has it.
2. Answer: Valid (Modus Tollens). The structure is $P \rightarrow Q$. The evidence is $eg Q$. The conclusion $eg P$ is a logically valid application of the contrapositive.
3. Answer: The green tea drinkers also exercised significantly more than the non-drinkers. This introduces an alternative cause for the reduced heart attacks, which weakens the claim that green tea was the specific factor responsible.
4. Answer: Invalid. While some warm-blooded creatures live in the ocean, they might not be the same warm-blooded creatures that are mammals (e.g., they could be birds). This is a classic "some" vs. "all" overlap error.
5. Answer: Post hoc ergo propter hoc (False Causality). The mayor assumes that because the decrease happened after the lanes were installed, the lanes caused the decrease.
6. Answer: Mistaken Negation. The premise says Allergic \u2192 Should Not Eat. The argument incorrectly assumes Not Allergic \u2192 Should Eat. There could be other reasons Sarah shouldn't eat it (e.g., she's allergic to honey).
7. Answer: Mark will not graduate with honors. Since both conditions (GPA \u2265 3.8 AND Thesis) are necessary, failing one condition is sufficient to guarantee he does not meet the requirement.
8. Answer: Reversing Cause and Effect. The argument takes a correlation and suggests the direction of causality is the opposite of what is commonly believed.
9. Answer: The definition of a "true fiscal conservative" excludes anyone who supports the new tax bill. The argument relies on this categorical definition being true to bridge the gap between the action and the label.
10. Answer: Show that on days when the team loses, the crime rate does not drop or actually increases. Establishing what happens in the absence of the cause (the win) helps solidify the causal link.

For more practice with similar logical structures, you may find Hard GRE Critical Reasoning Questions helpful as they share many formal logic foundations with the LSAT. If you are preparing for multiple exams, checking out our LSAT Prep hub is a great way to centralize your study materials.

Frequently Asked Questions

What is the best way to start studying for LSAT Logical Reasoning?

Begin by learning the basic structures of formal logic, specifically conditional statements and their contrapositives. Once you understand how to diagram arguments, practice identifying the specific question types to apply the correct strategy for each.

How much time should I spend on each Logical Reasoning question?

On average, you have about 1 minute and 24 seconds per question. However, easier questions at the start of the section should be completed in under a minute to save time for the more complex problems later on.

Can I use outside knowledge to answer LSAT questions?

No, you must rely strictly on the information provided in the stimulus. Bringing in outside facts can often lead you to choose "distractor" answers that are factually true but logically irrelevant to the specific argument provided.

What is the difference between a premise and an assumption?

A premise is an explicit piece of evidence stated in the text to support the conclusion. An assumption is an unstated piece of information that the author takes for granted as true to make the argument work.

How can I improve my speed in the Logical Reasoning section?

Improvement comes from pattern recognition; the more questions you solve, the faster you will identify common flaws and argument structures. Using an AI Exam Simulator can help you build the stamina and pacing needed for the real test.

What are common trap answers in Logical Reasoning?

Common traps include answers that are "too strong" (using words like "all" or "never" when the stimulus is moderate), answers that are true but don't answer the specific question, and answers that reverse the logic of the stimulus.