Hard GRE Inference Questions Practice Questions

Concept Explanation

An inference on the GRE is a statement that must be true based solely on the information provided in the passage, without requiring any outside assumptions or logical leaps.

Unlike "detail" questions that ask you to locate specific facts, Hard GRE Inference Questions require you to synthesize multiple pieces of information or recognize the logical implications of the author's tone and structure. Success on these difficult items depends on your ability to avoid "could be true" traps. In the context of GRE Prep, an inference is not a guess; it is a mathematical-like deduction. If the passage says "All A are B" and "Some B are C," you cannot infer that "Some A are C," but you can infer that "Anything that is not B is also not A."

To tackle high-difficulty inference tasks, follow these rigorous steps:

• Stick to the Text: If a choice requires a "maybe" or a "probably," it is wrong.
• Identify the Scope: Hard questions often use extreme language (always, never, only) in wrong answers to tempt students.
• Look for Combinations: Often, the answer is found by combining a fact from the first paragraph with a constraint mentioned in the second.
• Use the Negation Test: If you are unsure, ask: "If this choice were false, would it contradict the passage?" If yes, it is a valid inference.

Solved Examples

Review these worked examples to understand the logic required for GRE Inference Questions Practice Questions at a high difficulty level.

1. Passage: While most 19th-century novelists focused on the domestic sphere to critique societal rigidities, Clara Vance’s later works shifted toward the industrial landscape. However, Vance never abandoned her signature use of the unreliable narrator, a technique her contemporaries largely associated with gothic horror rather than social realism.
   Question: Which of the following can be inferred about Vance’s contemporaries?
   Solution:
   1. Analyze the constraints: Contemporaries associated unreliable narrators with gothic horror.
   2. Analyze Vance: She used unreliable narrators in works focusing on the industrial landscape (social realism).
   3. Deduce: If the contemporaries viewed the technique as a staple of gothic horror, they likely viewed its use in social realism as unconventional or atypical.
   4. Inference: Some of Vance’s contemporaries likely viewed her use of unreliable narrators in industrial settings as a departure from the standard conventions of social realism.
2. Passage: The presence of the $\text{L-type}$ calcium channel is necessary for the contraction of cardiac muscle. Experimental drug $X$ inhibits the $\text{L-type}$ channel but has no effect on the $\text{T-type}$ calcium channels found in skeletal muscle.
   Question: What must be true according to the passage?
   Solution:
   1. Identify the requirement: Cardiac contraction requires $\text{L-type}$ channels.
   2. Identify the drug action: Drug $X$ blocks $\text{L-type}$ channels.
   3. Logical link: If the channel necessary for contraction is blocked, the contraction cannot occur.
   4. Inference: The administration of Drug $X$ will hinder the contraction of cardiac muscle.
3. Passage: Historians argue that the 1924 Act significantly limited immigration from Southern Europe. Interestingly, the total number of immigrants from that region did not drop until 1926, when new administrative quotas were strictly enforced by local consulates.
   Question: What can be inferred about the years 1924 and 1925?
   Solution:
   1. Fact 1: The Act was passed in 1924.
   2. Fact 2: The total number of immigrants did not drop until 1926.
   3. Fact 3: Enforcement in 1926 caused the drop.
   4. Inference: In 1924 and 1925, the 1924 Act was not yet achieving its intended effect of reducing the total number of Southern European immigrants.

Practice Questions

Test your skills with these Hard GRE Inference Questions. Remember to look for the answer that must be true based on the text.

1. Passage: In the late Devonian period, many species of placoderm fish went extinct. This coincided with a significant drop in global sea levels and a cooling of tropical waters. However, deep-sea species survived at a much higher rate than those inhabiting shallow coastal reefs.

Which of the following is most strongly supported by the passage?

2. Passage: Critics of the new tax policy argue it will discourage investment by reducing the net return on capital. However, proponents point out that the policy includes a 100% deduction for research and development (R&D) expenses, which was not available under the previous tax code.

If the proponents' claim is true, which of the following must also be true?

3. Passage: All known members of the genus Archaeopteryx possessed feathers. While some paleontologists argue these feathers were used for flight, others suggest they were primarily for thermoregulation. No fossil evidence has yet been found of an Archaeopteryx with the skeletal structure required for sustained flapping flight.

Which of the following can be inferred from the passage?

4. Passage: The city's transit authority reported that ridership increased by 15% after the introduction of the new rapid-bus lanes. During the same period, the price of gasoline rose by 25%. The authority claims the new lanes are the primary driver of the ridership spike.

The passage suggests that the authority's claim would be weakened if which of the following were true?

5. Passage: Neuroscientists have discovered that the hippocampus is smaller in individuals with chronic stress. However, it is unclear whether stress causes the shrinkage or if individuals with a smaller hippocampus are more susceptible to stress. A recent study showed that successful treatment of stress does not lead to an increase in hippocampal volume.

Which of the following is most supported by the study mentioned?

6. Passage: Ethical intuitionism suggests that moral truths are self-evident to a rational mind. In contrast, moral skepticism argues that because different cultures have radically different moral codes, there are no objective moral truths.

Based on the passage, a moral skeptic would likely disagree with which of the following?

7. Passage: Most high-efficiency solar panels use monocrystalline silicon. While thin-film panels are cheaper to produce, they convert significantly less sunlight into electricity per square meter. A new startup has developed a thin-film panel that matches the efficiency of standard monocrystalline panels.

Which of the following can be inferred about the new startup's product?

8. Passage: The 18th-century philosopher David Hume argued that we cannot derive an "ought" from an "is." This means that no amount of factual information about the world can, by itself, lead to a moral conclusion. For example, the fact that a certain behavior is natural does not logically imply that it is good.

Which of the following follows from Hume's logic?

Answers & Explanations

1. Answer: Shallow coastal reefs were more affected by the late Devonian environmental changes than deep-sea habitats.
   Explanation: The passage states that deep-sea species survived at a higher rate. Since the extinction coincided with sea-level drops and cooling, and shallow-water species died more frequently, we can infer the environmental impact was more severe in those shallow areas.
2. Answer: The new tax policy treats R&D spending differently than the previous tax code did.
   Explanation: The passage explicitly states that the 100% deduction was "not available under the previous tax code." This is a direct inference from the text.
3. Answer: If the Archaeopteryx used its feathers for flight, it was likely not sustained flapping flight.
   Explanation: The text states there is no evidence for the skeletal structure needed for sustained flapping flight. Therefore, any flight that occurred must have been of a different kind (like gliding).
4. Answer: Gasoline price increases are known to cause significant shifts from car travel to public transit.
   Explanation: This would provide an alternative explanation for the ridership increase, thereby weakening the authority's claim that the bus lanes were the "primary driver."
5. Answer: Recovering from stress does not reverse hippocampal shrinkage.
   Explanation: The study found that successful treatment (recovery) did not lead to an increase in volume, supporting the idea that the shrinkage is either permanent or not caused by stress in a reversible way.
6. Answer: There is at least one moral truth that is universally recognizable through reason.
   Explanation: Skeptics believe there are no objective moral truths. Therefore, they would disagree with the idea that any moral truth is self-evident or universal.
7. Answer: The new product likely has a lower production cost per watt than standard monocrystalline panels.
   Explanation: Since thin-film is "cheaper to produce" and this specific one now matches the efficiency of monocrystalline, it combines the cost advantage of thin-film with the performance of silicon.
8. Answer: A list of biological facts about human nature is insufficient to establish a system of ethics.
   Explanation: This directly mirrors Hume's "is-ought" problem: facts ("is") cannot create moral conclusions ("ought").

1. If a passage states that "No professional athlete in the league has ever failed the new drug test," which of the following must be true?

• AAll professional athletes in the league have taken the new drug test.
• BThe new drug test is incapable of detecting certain prohibited substances.
• CAny athlete who failed a drug test is not a professional in this league.
• DProfessional athletes are more likely to pass tests than amateur athletes.

Frequently Asked Questions

What makes an inference question "hard" on the GRE?

Hard inference questions often use subtle language, complex sentence structures, and "distractor" options that are plausible in the real world but not supported by the specific text provided. They require synthesizing information from different parts of a passage rather than just one sentence.

How is an inference different from an assumption?

An inference is a conclusion that follows from the evidence provided, whereas an assumption is unstated evidence required for a conclusion to be true. On the GRE, you are looking for what is logically proven by the text.

Should I use my outside knowledge for GRE Reading Comprehension?

No, you should never use outside knowledge to answer GRE inference questions. Even if a statement is scientifically or historically true in real life, if it isn't supported by the passage, it is an incorrect answer choice.

Can an inference be a restatement of a sentence in the passage?

While an inference is technically a logical consequence, the GRE often uses "restatements in disguise" as correct answers. If an answer choice says exactly what the passage says but uses synonyms, it is a valid inference because it must be true.

What are common trap answers in Hard GRE Inference Questions?

Common traps include "could be true" statements, extreme language (all, never, only), and "out of scope" information. Another frequent trap is the "reversed relationship," where the choice flips the cause and effect mentioned in the passage.