LSAT Logical Reasoning Quiz: Inference
20 questions · exam conditions
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InferenceQuestion 1 of 20

In a city, 75% of the population uses public transportation, while 40% of those using public transportation report dissatisfaction with the service. Which one of the following must be true on the basis of the information above?

At least 30% of the city's population is dissatisfied with public transportation.
The majority of the population is satisfied with public transportation.
Public transportation is used by more people than those who own cars.
Some people who use public transportation are satisfied with the service.
More people are dissatisfied with public transportation than are satisfied.
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LSAT Logical Reasoning Quiz

LSAT Logical Reasoning Quiz: Inference

Practice Inference in LSAT Logical Reasoning with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Inference, giving you a quick way to practice the rules, question types, and explanations that matter most for LSAT Logical Reasoning.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

In a city, 75% of the population uses public transportation, while 40% of those using public transportation report dissatisfaction with the service. Which one of the following must be true on the basis of the information above?

  1. At least 30% of the city's population is dissatisfied with public transportation.
  2. The majority of the population is satisfied with public transportation.
  3. Public transportation is used by more people than those who own cars.
  4. Some people who use public transportation are satisfied with the service. (correct answer)
  5. More people are dissatisfied with public transportation than are satisfied.
Explanation: The stimulus tells us that 75% of the population uses public transportation, and 40% of those users report dissatisfaction. This means 60% of public transportation users are satisfied with the service. Since 75% use public transportation and 60% of those users are satisfied, there definitely exist people who both use public transportation and are satisfied with it. The exact number would be 60% of 75% of the population, which is positive. Choice A is tempting because it calculates 40% of 75% (approximately 30% of total population), but this represents dissatisfied users, not necessarily those who don't use public transport. When dealing with nested percentages, carefully track which group each percentage refers to and what logical relationships must exist.

Question 2

An urban survey asked respondents whether they own a car and whether they own a bicycle. Sixty percent reported owning a car, and thirty percent reported owning a bicycle. Among bicycle owners, 40 percent reported not owning a car. No respondent left either question unanswered, and there were no other options. Percentages are of all respondents. The survey sampled one neighborhood.

The information above supports which of the following conclusions?

  1. Most respondents own both a car and a bicycle.
  2. Fewer than half of respondents own a car.
  3. No respondent owns neither a car nor a bicycle.
  4. At least some respondents own both a car and a bicycle. (correct answer)
  5. All bicycle owners also own cars.
Explanation: If 40 percent of bicycle owners do not own a car, then 60 percent do own a car, so some respondents own both. The other options are not supported or contradict the given percentages.

Question 3

Factories that emit pollutant X must file an annual emissions report. If a filed report shows emissions above the legal threshold, the factory is fined. Audits, conducted at random, can detect unreported emissions. When a factory fails to file, any fine assessed for an audit-detected excess is twice what it would have been for the same excess had the factory filed. Factories that do not exceed the threshold are not fined.

The information above most strongly supports which of the following?

  1. A factory that files a timely report showing no excess is thereby exempted from the random audits that would otherwise detect its unreported emissions in future reporting years.
  2. Any factory that fails to file its annual emissions report will eventually be fined, whether or not a random audit ever detects an unreported excess at that facility.
  3. Audits that detect unreported emissions occur only at those factories whose previously filed reports already indicate emissions above the legal threshold for pollutant X.
  4. A factory that files a report showing an excess will always pay a smaller fine than a factory that fails to file the same excess but is never selected for a random audit.
  5. A factory that exceeds the legal threshold, fails to file, and is caught by an audit will be fined more than it would have been fined had it filed with the same emissions. (correct answer)
Explanation: The passage says a fine for an audit-detected excess at a non-filer is twice what the same excess would have cost had the factory filed. So a factory that exceeds the threshold, fails to file, and is caught pays double — clearly more than it would have paid by filing. That is directly supported. The option about a no-excess filer being exempted from audits contradicts the passage: audits are conducted at random, not triggered or blocked by any report. The option that every non-filer is eventually fined ignores that a fine requires an audit-detected excess; a non-filer who is never audited, or one below the threshold, pays nothing. The option that audits happen only where filed reports already show an excess again contradicts the random nature of audits, which exist precisely to catch unreported emissions. The option that a reporting factory always pays less than an unaudited non-filer fails because an unaudited non-filer with an excess pays nothing at all, so the reporter does not pay less — it pays more.

Question 4

Two hundred runners registered for a Saturday trail race. On race morning, 10 percent of registrants did not start. Of those who started, all but five finished; the rest dropped out due to heat. The race director confirmed that no unregistered runners started and that every finisher was a registrant. Timing chips registered only one finish per runner. No one was disqualified.

Which of the following can be inferred from the information above?

  1. Fewer than 170 runners finished the race.
  2. Exactly 175 runners finished the race. (correct answer)
  3. More than 25 runners did not start.
  4. Exactly five unregistered runners finished.
  5. All 200 registrants started the race.
Explanation: Twenty registrants did not start (10 percent of 200), leaving 180 starters; with five dropping out, 175 finished. All other options contradict the stated numbers.

Question 5

A transit card can be used on buses, trains, or ferries. Every ride on a ferry requires a reservation. No bus ride requires a reservation. Some train rides require a reservation and some do not. Ride R required a reservation and was either a bus ride or a train ride. Which one of the following must be true on the basis of the information above?

  1. Ride R was a bus ride.
  2. Ride R was a train ride. (correct answer)
  3. Ride R was a ferry ride.
  4. No train rides require reservations.
  5. All rides that require reservations are ferry rides.
Explanation: The transit card rules establish that ferry rides require reservations, bus rides don't require reservations, and train rides are mixed (some require reservations, some don't). Ride R required a reservation and was either a bus or train ride. Since bus rides don't require reservations, and R did require a reservation, R cannot have been a bus ride. Therefore, R must have been a train ride. This is a straightforward application of exclusionary logic - when one option is ruled out by incompatible characteristics, the remaining option must be correct. Choice A is impossible because bus rides don't require reservations. This demonstrates how definitive rules about requirements can eliminate possibilities and force specific conclusions.

Question 6

During finals week, the university library extends closing time to 2 a.m. A posted notice states: food is allowed only in designated areas; study rooms must be reserved through the online system; after 10 p.m., only students presenting a valid university ID will be admitted. The library cafe closes at 9 p.m. Weekday daytime hours remain unchanged, and guests are welcome during daytime. Security staff monitor the main entrance after 9:45 p.m.

Which of the following can be inferred from the information above?

  1. Students may eat in any study room after 10 p.m.
  2. Non-students must leave the library by 10 p.m.
  3. Study rooms can be reserved only in person at the front desk.
  4. The cafe remains open until 10 p.m. during finals week.
  5. A visitor without a university ID who arrives at 11 p.m. will be denied entry. (correct answer)
Explanation: After 10 p.m., only students with valid IDs are admitted, so a visitor without one arriving at 11 p.m. cannot enter. The other options add assumptions about eating, departures, reservation methods, or cafe hours not supported by the notice.

Question 7

In a clinical trial, participants were assigned to a Drug group or a Placebo group. A participant was counted as a completer only if they attended all three monthly visits. Of 240 participants, 150 were assigned to Drug. Overall, 180 attended the first visit, 170 the second, and 160 the third. Exactly 140 participants attended all three visits; of these completers, 20 were in the Placebo group.

Which of the following is most strongly supported by the information above?

  1. Exactly 30 Drug-group participants missed the first visit.
  2. At most 120 Drug-group participants attended any visit.
  3. No Placebo-group participant attended all three visits.
  4. At least 30 Drug-group participants failed to complete all three visits. (correct answer)
  5. Fewer than 140 participants attended the second visit.
Explanation: If 140 completed all visits and 20 of those were Placebo, then 120 Drug participants completed all visits. Since 150 participants were assigned to the Drug group, at least 30 Drug participants did not complete. A, B, and E assert specific visit attendance counts not established, and C contradicts the stated number of Placebo completers.

Question 8

At Apex Co., every employee is either staff or contractor. There are 120 employees, including 20 contractors. For a mandatory safety seminar, exactly 50 staff members attended, and all 15 managers (all of whom are staff) were among those attendees. Managers are a subset of staff; no contractors are managers. Attendance figures were recorded only for staff, not contractors. No other employees were counted as attending.

The information above most strongly supports which of the following?

  1. Exactly 50 non-manager staff members did not attend the seminar. (correct answer)
  2. At least one contractor attended the seminar.
  3. Fewer than half of all employees attended the seminar.
  4. All contractors failed to attend the seminar.
  5. More contractors than managers attended the seminar.
Explanation: Staff total 100 (120 minus 20 contractors); with 50 staff attending and all 15 managers attending, exactly 50 non-manager staff did not attend. The other choices speculate about contractor attendance or totals not fixed by the facts.

Question 9

A department's search committee reviews only applicants who meet both minimums: at least five peer-reviewed publications and recent teaching evaluations averaging 4.0 or higher. If, by the posted deadline, fewer than three applicants meet both minimums, the committee must extend the deadline; interviews may begin only after the application period ends. This year, no deadline extensions occurred, and interviews began on May 10. The committee cannot alter the minimums during a search.

Which of the following can be properly inferred from the information above?

  1. No applicant with fewer than five publications applied.
  2. Exactly three applicants met both minimums.
  3. Interviews began before the application period ended.
  4. At least three applicants met both minimums by the posted deadline. (correct answer)
  5. The committee extended the deadline in previous years.
Explanation: Because a deadline extension is mandatory if fewer than three meet both minimums and no extension occurred, at least three applicants met both by the deadline. The other options assert exact counts, contradict the timeline, or add unsupported historical claims.

Question 10

At Parkside Café, a student discount of 10 percent is given only to customers who present a valid student ID at purchase. A separate senior discount is available on Tuesdays to customers aged 65 or older. Discounts cannot be combined, and the cashier must choose the highest single applicable discount. Customers not meeting a discount's stated requirement receive no discount. No other discounts are offered.

Which of the following is best supported by the information above?

  1. On Tuesdays, any customer who shows any form of identification receives some discount.
  2. A 70-year-old who presents a valid student ID on Tuesday will receive the student discount rather than the senior discount.
  3. A 20-year-old student who purchases on Tuesday without a valid student ID will pay full price. (correct answer)
  4. A 70-year-old who purchases on Wednesday will pay full price.
  5. Students always receive 10 percent off regardless of the day or ID.
Explanation: Without a valid student ID and not being 65 or older, the 20-year-old meets no discount requirement and thus pays full price. The other options introduce unsupported assumptions about which discount applies or imply discounts when requirements are unmet.

Question 11

An academic journal sent submissions for peer review if and only if they both stated a clear hypothesis and described replicable methods. Every sent paper received at least two reviews; no unsent paper received any review. Of 120 submissions, exactly 58 stated a clear hypothesis. Exactly 42 lacked replicable methods; among these, 15 nevertheless stated a clear hypothesis. All other submissions met the methods requirement.

Which of the following can be inferred from the information above?

  1. Exactly 86 total reviews were completed.
  2. Exactly 43 submissions were sent for peer review. (correct answer)
  3. No submission lacking a clear hypothesis was submitted to the journal.
  4. At least 78 submissions lacked replicable methods.
  5. Some submissions received only one review.
Explanation: Of 58 with clear hypotheses, 15 lacked methods, leaving 43 with both criteria; by the biconditional policy, exactly those 43 were sent. A and E misstate review counts, since only a minimum of two per sent paper is known. C confuses submission with review eligibility, and D reverses the given count of methods.

Question 12

A science fair awards ribbons in three colors: gold, silver, and bronze. No project receives more than one ribbon. Every project that receives gold is judged in the advanced division. Some projects judged in the advanced division receive silver. Project Q was not judged in the advanced division. Which one of the following must be true on the basis of the information above?

  1. Project Q received bronze.
  2. Project Q did not receive gold. (correct answer)
  3. Project Q received silver.
  4. All silver-ribbon projects are judged in the advanced division.
  5. Some gold-ribbon projects are not judged in the advanced division.
Explanation: The science fair ribbon system establishes that all gold-ribbon projects are judged in the advanced division, while some advanced division projects receive silver. Project Q was not judged in the advanced division. By contrapositive reasoning, since all gold recipients are in advanced division, any project not in advanced division cannot have received gold. Therefore, Project Q did not receive gold. Choice A is tempting because bronze is a possibility, but we cannot determine the specific ribbon color - only that it wasn't gold. This problem illustrates the power of contrapositive reasoning in eliminating possibilities. When 'all A are B' and something is 'not B,' it cannot be A.

Question 13

In a town, if fine-particulate pollution exceeds the legal threshold on three days within a calendar month, an automatic ban on residential wood burning is imposed for the remainder of that month. Monitors sometimes go offline; when that happens, missed readings cannot be reconstructed, and bans are not imposed retroactively. This January, a ban was in effect from the 20th through the 31st. Two early-January days had monitor outages.

Which of the following is most strongly supported by the information above?

  1. The town exceeded the threshold exactly three times in January.
  2. The monitor outages caused the ban to start later than it otherwise would have.
  3. There were no threshold exceedances after the ban took effect.
  4. If the monitors had not gone offline, no ban would have been imposed.
  5. By the time the ban began, at least three January days had recorded exceedances. (correct answer)
Explanation: A ban begins only after three exceedance days occur, so at least three exceedances had occurred by the time the ban started. The other choices speculate about exact counts, the effects of outages, or post-ban levels without support.

Question 14

In June, a new ordinance banned overnight street parking. That month, police issued exactly 500 overnight parking tickets. A vehicle is booted only after receiving three such tickets, and records show that no vehicle received more than two overnight tickets in June. Tickets for other violations are tracked separately and are not included in those 500. Only one ticket per vehicle can be issued per night.

Which of the following can be inferred from the information above?

  1. Exactly 250 vehicles were ticketed for overnight parking in June.
  2. Some vehicles received overnight parking tickets on consecutive nights.
  3. No vehicle was booted in June for any reason.
  4. At most two tickets can be issued to a vehicle in a single month.
  5. At least 250 vehicles received one or more overnight parking tickets in June. (correct answer)
Explanation: With 500 tickets and no vehicle receiving more than two, at least 250 vehicles must have been ticketed. The other statements assert exact counts, unrelated booting, or month-wide rules not supported by the facts.

Question 15

At a conference keynote, attendees could ask questions only if they had Full passes and were seated in the first 10 rows. Of 900 attendees, 600 had Full passes. Four hundred attended the keynote; of those, exactly 250 sat in the first 10 rows, and no one without a Full pass sat in those rows. Exactly 220 questions were asked, and no attendee asked more than one question.

Which of the following can be inferred from the information above?

  1. All 400 keynote attendees had Full passes.
  2. Exactly 350 Full pass holders did not attend the keynote.
  3. At least 30 attendees sat in the first 10 rows without asking a question. (correct answer)
  4. Fewer than half of Full pass holders attended the keynote.
  5. At most 220 of the 250 in the first 10 rows had Full passes.
Explanation: Because only those in the first 10 rows with Full passes could ask, all 220 questioners came from the 250 seated there, and none asked more than one question. Therefore at least 30 seated in those rows did not ask a question. A, B, and D speculate about broader attendance or pass distribution, and E contradicts the statement that everyone in those rows had a Full pass.

Question 16

At a conference, each attendee joined at least one of three workshops: Front-end, Back-end, or UX. Exactly 120 attended Front-end, 90 attended Back-end, and 60 attended UX. No one attended all three. Exactly 30 attended both Front-end and Back-end, 20 attended both Back-end and UX, and 10 attended both Front-end and UX. The remaining attendees each joined only one workshop.

Which of the following can be inferred from the information above?

  1. Exactly 30 attendees joined both Front-end and Back-end and also attended UX.
  2. Exactly 80 attendees joined only Front-end. (correct answer)
  3. Exactly 60 attendees joined only UX.
  4. Exactly 40 attendees joined exactly two workshops.
  5. Exactly 50 attendees joined only Back-end.
Explanation: Only Front-end = 120 − 30 − 10 = 80. The other numerical claims contradict the given overlaps or require counts not supported by the data.

Question 17

In City X, a permit is required for amplified street performances. Permits are issued only to residents who are at least 18 years old, upon verification of age and residency. Last night, officers cited two amplified performers for lacking permits. Each presented valid proof of residence; one performer is 17 years old, and the other did not state an age. The ordinance does not allow exceptions for minors.

Which of the following can be inferred from the information above?

  1. Neither performer was a resident.
  2. Both performers were ineligible for permits.
  3. The 17-year-old was ineligible for a permit. (correct answer)
  4. The older performer definitely qualified for a permit.
  5. The citation was issued because the performers were minors.
Explanation: Permits are issued only to residents at least 18, so the 17-year-old is ineligible. The other choices assert residency, eligibility, or reasons for the citation that are not guaranteed.

Question 18

A software team tracked internal email responses for two months. Before implementing an after-hours auto-responder at 6 p.m., daytime messages were typically answered within two hours, whereas after-hours replies were slower. After adding the auto-responder, daytime response times did not change, and after-hours replies improved slightly but stayed slower than daytime. Team size, workload, and the number of daytime emails remained steady throughout the study.

Which of the following can be concluded on the basis of the information above?

  1. The auto-responder caused daytime responses to become faster.
  2. The team handled fewer daytime emails after the auto-responder was added.
  3. After the auto-responder, average after-hours responses were still slower than daytime responses. (correct answer)
  4. Without the auto-responder, after-hours response times matched daytime speeds.
  5. The auto-responder eliminated most after-hours delays.
Explanation: The passage states that after-hours replies improved but remained slower than daytime after the auto-responder. The other options contradict stated invariances or overstate the auto-responder's effects.

Question 19

A sandwich shop posts: free beverage refills apply only to dine-in orders and only for the same size of the same beverage; add-ins like syrups or boba are not refillable. During the lunch special, no substitutions are permitted. To-go orders do not qualify for refills. Refills must be requested at the counter. The shop closes at 8 p.m., but the soda fountain is shut down 15 minutes earlier for cleaning.

Which of the following is most strongly supported by the policy described above?

  1. Someone who purchased a to-go drink cannot receive a free refill. (correct answer)
  2. A dine-in customer may refill a small drink into a large cup.
  3. During the lunch special, substitutions are allowed if requested at the counter.
  4. Add-ins can be refilled for a fee.
  5. Refills are available until closing time.
Explanation: The policy explicitly states that to-go orders do not qualify for refills. The other choices contradict stated limits or introduce rules not mentioned.

Question 20

Last year, 40 percent of visits to the city art museum were by tourists. This year, total visits rose compared to last year, while the museum's records show that the number of tourist visits remained the same. The museum did not alter its visitor-counting methods, and admission policies were unchanged. No other categories of visitors were introduced. Special exhibitions were scheduled in both years.

The statements above most strongly support which of the following?

  1. The museum raised ticket prices this year.
  2. The number of local visits declined this year.
  3. A higher percentage of visits this year were by locals than last year. (correct answer)
  4. Tourists spent less time per visit this year than last year.
  5. The museum had fewer total visits this year than last year.
Explanation: With tourist visits unchanged and total visits higher, locals necessarily made up a larger share of visits. The other choices are not supported or contradict the premises.