Hard GRE Critical Reasoning Questions Practice Questions

Can a single logical flaw in an argument determine your entire verbal score? On the GRE Prep journey, mastering the short arguments found in the Verbal Reasoning section requires more than just reading comprehension; it demands a rigorous analysis of how premises support conclusions. Hard GRE Critical Reasoning Questions Practice Questions challenge students to identify unstated assumptions, evaluate the strength of evidence, and recognize subtle logical fallacies that often trip up even high-scoring test-takers.

Concept Explanation

Hard GRE Critical Reasoning Questions Practice Questions are specialized verbal tasks that evaluate your ability to analyze, evaluate, and construct arguments through short passages. These questions typically present a "stimulus" (an argument or set of facts) followed by a question stem that asks you to perform a specific logical operation. To succeed at the hardest levels, you must distinguish between the conclusion (the main point), the premises (the supporting evidence), and the assumptions (the unstated links between the two).

Common question types include:

• Strengthen/Weaken: Identifying information that makes the conclusion more or less likely to be true.
• Assumption: Finding the necessary but unstated premise that allows the argument to function.
• Boldface: Determining the structural role of specific sentences (e.g., is it a counter-premise or an intermediate conclusion?).
• Inference: Identifying what must be true based strictly on the provided facts.
• Paradox/Explain: Finding an answer choice that resolves a seeming contradiction between two facts.

Success on these difficult items often hinges on avoiding "trap" answers that are true in the real world but irrelevant to the specific logic of the passage. For more targeted training, students often use an AI Exam Simulator to mimic the adaptive nature of the actual test.

Solved Examples

1. Strengthening an Argument
Passage: A recent study found that people who eat at least one apple a day have 20% fewer cavities than those who do not. Therefore, the fiber in apples must help scrub teeth clean of plaque.
Question: Which of the following, if true, most strengthens the argument?
Solution:

1. Identify the conclusion: Fiber in apples scrubs teeth to prevent cavities.
2. Identify the premise: Apple eaters have 20% fewer cavities.
3. Look for a gap: The study shows a correlation, but the argument assumes fiber is the specific cause.
4. Evaluate options: An answer stating that "People who eat apples do not engage in other dental health practices more frequently than non-apple eaters" strengthens the argument by ruling out an alternative cause.

2. Identifying an Assumption
Passage: The city council plans to reduce traffic congestion by increasing the toll on the Main Street Bridge during rush hour. This plan will succeed because commuters are sensitive to costs.
Question: What is a necessary assumption of this plan?
Solution:

1. Conclusion: Increasing the toll will reduce congestion.
2. Premise: Commuters are cost-sensitive.
3. Find the missing link: For the plan to work, there must be an alternative for these cost-sensitive commuters.
4. Correct Assumption: There are viable alternative routes or modes of transport available to commuters currently using the Main Street Bridge.

3. Resolving a Paradox
Passage: In Country X, the number of people diagnosed with Disease Y has doubled over the last decade. However, the mortality rate from Disease Y has stayed exactly the same during that period.
Question: Which of the following most helps to explain the discrepancy?
Solution:

1. Identify the conflict: More diagnoses (more sick people), but no increase in the death rate.
2. Brainstorm: Perhaps the disease is caught earlier, or it has become less lethal.
3. Correct Explanation: Improved screening technology now allows doctors to detect mild cases of Disease Y that would have gone undiagnosed ten years ago.

Practice Questions

1. A tech company noticed that employees who use standing desks report 15% higher productivity than those who use traditional desks. The CEO concluded that installing standing desks for all employees will increase the company's overall output. Which of the following, if true, most weakens the CEO's conclusion?

2. Most species of the genus Arboris thrive only in soil with high nitrogen content. However, Arboris silva is frequently found in nitrogen-poor rocky outcrops. Biologists conclude that Arboris silva has developed a unique metabolic pathway to process atmospheric nitrogen. Which of the following is an assumption required by the biologists' argument?

3. The local government of Oakhaven recently banned all plastic straws in restaurants to reduce plastic waste in the ocean. However, critics argue that this ban will have no significant impact because plastic straws account for less than 0.05% of total ocean plastic by weight. The critics' reasoning is flawed, however, because it ignores the disproportionate harm straws cause to marine life compared to heavier plastic debris. What is the role of the two boldfaced portions?

4. Economists have observed that when the price of luxury watches increases, the demand for them often increases as well. This contradicts the standard law of demand, which states that as price rises, demand falls. Which of the following, if true, best explains this phenomenon?

5. To reduce the incidence of lung cancer, the government of Country Z increased the tax on cigarettes by 500%. Despite this, the total number of cigarette packs sold in Country Z remained unchanged over the following year. Which of the following, if true, best explains the failure of the tax to reduce cigarette sales?

6. Scientists have discovered that a specific enzyme, Alpha-7, is present in much higher concentrations in the brains of patients with Alzheimer's disease than in healthy individuals. They conclude that Alpha-7 is a primary cause of the neural degeneration associated with the disease. Which of the following, if true, most weakens the scientists' conclusion?

7. Editorial: The proposed high-speed rail line between City A and City B is a waste of taxpayer money. Only 10% of the population of City A currently travels to City B more than once a year. Therefore, the rail line will be underutilized. Which of the following is a flaw in the editorial's reasoning?

8. All members of the elite track team are required to maintain a GPA of 3.5 or higher. Since Marcus is on the elite track team, Marcus must have a high GPA. What is the logical structure of this argument?

Answers & Explanations

1. Answer: Employees who are naturally more productive are the ones most likely to request or purchase standing desks.
   Explanation: This suggests a "reverse causation" flaw. If the productivity caused the desk choice rather than the desk causing the productivity, then forcing desks on everyone won't help.
2. Answer: Arboris silva does not obtain nitrogen from symbiotic fungi that extract it from the rocks.
   Explanation: This is a necessary assumption because it rules out an alternative source of nitrogen. If fungi provided the nitrogen, the "unique metabolic pathway" theory would be unnecessary.
3. Answer: The first is a policy that the argument eventually defends; the second is the argument's main conclusion.
   Explanation: The first bold part introduces the context/policy, and the second part directly states the author's final position against the critics.
4. Answer: Consumers perceive higher-priced luxury watches as having higher social status, making them more desirable.
   Explanation: This resolves the paradox by introducing a new variable (social status) that outweighs the standard price-demand relationship.
5. Answer: A significant black market for untaxed cigarettes emerged in Country Z immediately following the tax hike.
   Explanation: This explains why official sales didn't drop; consumers simply bypassed the legal, taxed market to maintain their habits.
6. Answer: The brain produces Alpha-7 as a protective response to repair damage caused by neural degeneration.
   Explanation: This weakens the conclusion by suggesting that Alpha-7 is an effect of the disease, not the cause.
7. Answer: It fails to consider that the availability of high-speed rail might increase the frequency of travel between the two cities.
   Explanation: The editorial assumes current travel patterns are fixed, ignoring how the new service itself could create new demand.
8. Answer: It applies a general rule to a specific individual who belongs to the group governed by that rule.
   Explanation: This is a classic deductive argument: All A are B; X is A; therefore X is B.

1. Which of the following best describes an "assumption" in a GRE Critical Reasoning context?

• AA summary of the main conclusion
• BEvidence explicitly stated in the passage
• CAn unstated premise necessary for the conclusion to be valid
• DA counter-argument provided by an opponent

Frequently Asked Questions

How many Critical Reasoning questions are on the GRE?

The GRE Verbal Reasoning section typically includes about 1 to 2 Critical Reasoning questions per 20-question block. While they are fewer in number than Reading Comprehension or Text Completion items, their high difficulty level makes them crucial for a top score.

What is the "Negation Test" for assumption questions?

The Negation Test involves taking an answer choice and turning it into its logical opposite. If the negated version of the choice completely destroys the argument's validity, then that choice is the necessary assumption.

Can I use outside knowledge to answer these questions?

No, you must rely strictly on the information provided in the passage. Hard GRE Critical Reasoning Questions Practice Questions often include "common sense" traps that are true in reality but logically irrelevant to the specific argument presented.

Why are Boldface questions considered the hardest?

Boldface questions are difficult because they require a high-level understanding of abstract logical structure. You aren't just reading for content; you are identifying the "job" each sentence performs within the overall architecture of the argument.

Should I read the question stem before the passage?

Many experts recommend reading the question stem first so you know exactly what logical task to perform (e.g., weakening, strengthening, or finding an assumption) while reading the passage. This helps you focus on the relationship between premises and conclusions immediately.