Inference questions give you a set of facts and ask what must be true, or what is most strongly supported, on the basis of them. Unlike most Critical Reasoning types in the GMAT Focus Verbal section, there is usually no argument to attack: the passage is evidence, and you are drawing the conclusion.
The standard is strict. The right answer must follow from the statements given, with no outside knowledge and no assumptions. That makes the correct choice look modest, often almost dull, while the wrong choices sound insightful because they go a step beyond the text.
Look for statements that combine. Inference questions often place two facts in different sentences that only produce a conclusion together: if every product in a range was tested and one product failed, then at least one product in the range failed a test. Numbers are common too. If market share went up while total sales went down, the passage has told you something about competitors.
Eliminate on language. Words such as “always”, “most” and “will” are hard to prove, while “some”, “can” and “at least one” are easy. Reject a choice the moment it needs information the passage does not give, however plausible it seems in real life.
4 practice questions
Critical ReasoningInferenceEasy
Question 1
Every specimen in the Halden Museum's meteorite collection is classified as exactly one of the following: stony, iron, or stony-iron. Every specimen in the collection that contains chondrules, small rounded grains of once-molten rock, is classified as stony. All of the collection's specimens that were recovered in Antarctica contain chondrules. The collection includes at least one stony-iron specimen, which is currently on display in the museum's main hall.
If the statements above are true, which of the following must also be true?
AEvery stony specimen in the Halden Museum's collection contains chondrules.
BAt least one specimen recovered in Antarctica is on display in the museum's main hall.
CAt least one of the collection's iron specimens was recovered in Antarctica.
DMost of the collection's stony specimens were recovered in Antarctica.
ENone of the collection's stony-iron specimens was recovered in Antarctica.
Show answer & explanation
Correct answer: E
Key Concept or Approach
Chain the conditional statements: recovered in Antarctica, therefore contains chondrules, therefore stony. Since each specimen has exactly one classification, a stony specimen cannot be stony-iron.
Step-by-Step Solution
Step 1: Identify the task (Inference) and the gap in the reasoning: Chain the conditional statements: recovered in Antarctica, therefore contains chondrules, therefore stony. Since each specimen has exactly one classification, a stony specimen cannot be stony-iron.
Step 2: (E) Correct. Any Antarctic specimen contains chondrules and so is stony; because classifications are exclusive, it cannot be stony-iron. So no stony-iron specimen came from Antarctica.
Step 3: (A) This reverses the conditional. Chondrules guarantee a stony classification, but a stony specimen need not contain chondrules.
Step 4: (B) Nothing is said about which Antarctic specimens, if any, are on display; the only displayed specimen mentioned is stony-iron.
Step 5: (C) This cannot be true: every Antarctic specimen contains chondrules and is therefore stony, so no iron specimen can have come from Antarctica.
Step 6: (D) The passage gives no numbers, so it cannot tell us what share of stony specimens came from Antarctica.
Final Answer
Answer: E
Common trap: A is tempting because it reverses a rule the passage states ('chondrules means stony'), but the reverse ('stony means chondrules') is never given.
Critical ReasoningInferenceEasy
Question 2
In the town of Pellham, restaurants may serve food after midnight only if they hold a late-night license. Town records show that every Pellham restaurant holding a late-night license closes its outdoor seating area by 10 p.m. No restaurant can obtain a late-night license unless it has passed a noise inspection within the past year. The Gilded Fork, a Pellham restaurant, keeps its outdoor seating area open until 11 p.m. every night.
If the statements above are true, which of the following must also be true?
AThe Gilded Fork does not hold a late-night license.
BThe Gilded Fork has not passed a noise inspection within the past year.
CNo Pellham restaurant that has outdoor seating holds a late-night license.
DEvery Pellham restaurant that has passed a noise inspection within the past year holds a late-night license.
EThe Gilded Fork stops serving food before 11 p.m.
Show answer & explanation
Correct answer: A
Key Concept or Approach
Every licensed restaurant closes its outdoor seating by 10 p.m. The Gilded Fork's stays open until 11 p.m., so the Gilded Fork cannot be licensed.
Step-by-Step Solution
Step 1: Identify the task (Inference) and the gap in the reasoning: Every licensed restaurant closes its outdoor seating by 10 p.m. The Gilded Fork's stays open until 11 p.m., so the Gilded Fork cannot be licensed.
Step 2: (A) Correct. This follows directly (contrapositive).
Step 3: (B) A passed inspection is necessary for a license, not sufficient. The Gilded Fork may have passed and still not hold a license.
Step 4: (C) Licensed restaurants can have outdoor seating as long as they close it by 10 p.m.
Step 5: (D) This reverses the conditional: an inspection is required for a license but does not guarantee one.
Step 6: (E) The passage says nothing about when the Gilded Fork stops serving food, only that it cannot serve after midnight.
Final Answer
Answer: A
Common trap: B is tempting because it confuses a necessary condition (a passed inspection) with a sufficient one.
Critical ReasoningInferenceHard
Question 3
Each of Corvel Manufacturing's factories is either unionized or non-unionized. Last year, the average wage per hour worked at Corvel's unionized factories was higher than at its non-unionized factories. Compared with the year before, last year the average wage per hour worked rose at the unionized factories, and it also rose at the non-unionized factories. Nevertheless, the average wage per hour worked across all of Corvel's factories combined was lower last year than the year before.
If the statements above are true, which of the following must also be true?
ACorvel closed at least one unionized factory last year.
BThe average wage per hour worked rose by less at the unionized factories than at the non-unionized factories.
CThe total number of hours worked at Corvel's non-unionized factories was greater last year than the year before.
DCorvel's total spending on wages was lower last year than the year before.
EThe share of all hours worked at Corvel that were worked at unionized factories was smaller last year than the year before.
Show answer & explanation
Correct answer: E
Key Concept or Approach
The overall average is a weighted average of the two group averages, weighted by each group's share of hours. Both group averages rose, yet the overall average fell. That can happen only if the weight shifted toward the lower-paying group, which last year was the non-unionized factories.
Step-by-Step Solution
Step 1: Identify the task (Inference) and the gap in the reasoning: The overall average is a weighted average of the two group averages, weighted by each group's share of hours. Both group averages rose, yet the overall average fell. That can happen only if the weight shifted toward the lower-paying group, which last year was the non-unionized factories.
Step 2: (E) Correct. Both group averages rose, so the combined average could fall only if unionized pay was also higher the year before. Given that, a steady or larger unionized share of hours would have pushed the combined average up, not down, so the unionized share must have shrunk.
Step 3: (A) The share of hours could shift without any closure, for example through reduced shifts at unionized plants.
Step 4: (B) The relative size of the raises need not follow. The overall drop comes from the change in mix.
Step 5: (C) Unionized hours could have fallen sharply while non-unionized hours fell a little or stayed flat. Non-unionized hours need not have increased.
Step 6: (D) Total wage spending depends on total hours, which the passage does not give.
Final Answer
Answer: E
Common trap: C is tempting because a shift toward non-unionized work sounds like more non-unionized hours, but the shift is in share, which can happen with unionized hours falling instead.
Critical ReasoningInferenceVery hard
Question 4
A 2015 government report warned that Orvania's pharmacies would struggle to keep up with demand as the country's population aged, and it recommended expanding pharmacy training programs. Those programs were expanded the following year. As a result, the number of licensed pharmacists in Orvania increased by 20 percent between 2015 and 2025, while the population increased by 5 percent. Over the same period, the total number of prescriptions filled in Orvania increased by 30 percent.
If the statements above are true, which of the following must also be true?
AThe number of licensed pharmacists per resident of Orvania increased by more than 15 percent between 2015 and 2025.
BThe number of prescriptions filled per resident of Orvania increased by more than 25 percent between 2015 and 2025.
CBetween 2015 and 2025, the number of prescriptions filled per licensed pharmacist in Orvania increased by a smaller percentage than did the number of prescriptions filled per resident.
DMore than 20 percent of the prescriptions filled in Orvania in 2025 were filled by pharmacists licensed after 2015.
EThe number of prescriptions filled per licensed pharmacist in Orvania increased by at least 10 percent between 2015 and 2025.
Show answer & explanation
Correct answer: C
Key Concept or Approach
Percentage changes in ratios are found by dividing growth factors, not subtracting percentages. Prescriptions per pharmacist: 1.30 / 1.20 = about 1.083 (+8.3%). Prescriptions per resident: 1.30 / 1.05 = about 1.238 (+23.8%). Pharmacists per resident: 1.20 / 1.05 = about 1.143 (+14.3%).
Step-by-Step Solution
Step 1: Identify the task (Inference) and the gap in the reasoning: Percentage changes in ratios are found by dividing growth factors, not subtracting percentages. Prescriptions per pharmacist: 1.30 / 1.20 = about 1.083 (+8.3%). Prescriptions per resident: 1.30 / 1.05 = about 1.238 (+23.8%). Pharmacists per resident: 1.20 / 1.05 = about 1.143 (+14.3%).
Step 2: (C) Correct. Per pharmacist rose about 8.3 percent and per resident about 23.8 percent, so the per-pharmacist increase was the smaller one. This follows from the figures whatever the starting values.
Step 3: (A) Subtracting 5 from 20 suggests 15 percent, but the true increase is 1.20 / 1.05 - 1, about 14.3 percent, which is less than 15.
Step 4: (B) The increase is 1.30 / 1.05 - 1, about 23.8 percent, not more than 25 percent.
Step 5: (D) The passage says nothing about which pharmacists filled which prescriptions, so this cannot be inferred.
Step 6: (E) Subtracting 20 from 30 suggests 10 percent, but the true increase is 1.30 / 1.20 - 1, about 8.3 percent.
Final Answer
Answer: C
Common trap: E is tempting because 30 percent minus 20 percent equals 10 percent, but percentage changes in a ratio must be divided, giving only about 8.3 percent.
