Critical Reasoning
Critical Reasoning – Quick Theory
Critical Reasoning (CR) tests your ability to analyse arguments, detect hidden assumptions, spot logical flaws and draw valid conclusions. Every CR item has three parts:
- Stimulus – a short passage that contains an argument or a set of facts.
- Question stem – tells you what to do (strengthen, weaken, find assumption, draw inference, etc.).
- Answer choices – one correct and three tempting but wrong options.
In Railway exams the passages are 40–60 words long and the errors are standard: causation vs. correlation, over-generalisation, circular reasoning, equivocation and surveys without representativeness.
Master the “filter” technique: first read the question stem, then the passage; this keeps you goal-oriented and saves 15–20 s per item.
Practice Set – 25 MCQs
Directions: Read the short passage and choose the best answer.
-
(Easy)
Passage: All the trains that run on time are powered by electricity. The Rajdhani always arrives on time.
Conclusion: The Rajdhani is powered by electricity.
The conclusion is
A. certainly true
B. probably true
C. probably false
D. certainly false -
(Easy)
Passage: In 2022, Station X installed CCTV cameras on every platform. In 2023, the number of reported thefts dropped by 30 %.
Claim: CCTV cameras caused the drop in thefts.
Which fact would most weaken the claim?
A. A new police booth was opened in 2023.
B. CCTV footage is stored for 30 days.
C. The station master was transferred in 2022.
D. Passenger traffic remained the same. -
(Medium)
Passage: To reduce track deaths, Railways decided to fence off the entire 300 km stretch in State Y. Critics say the move is wasteful because last year only 10 % of track deaths in State Y occurred on that stretch.
Which assumption is necessary for the critics’ argument?
A. Fencing is the only way to save lives.
B. The cost of fencing is disproportionate to lives saved on that stretch.
C. Track deaths will increase in other states.
D. Passengers will protest the fencing. -
(Medium)
Passage: 80 % of Railway apprentices who came through the RRB exam in 2021 scored above 80 % in their ITI course.
Inference: The RRB exam selects academically bright candidates.
The inference is
A. logically valid
B. valid if ITI marks predict brightness
C. invalid because it ignores the 20 %
D. invalid because correlation is not causation -
(Hard)
Passage: Dynamic fare pricing has increased the cost of Rajdhani tickets by 25 %, yet occupancy has risen by 10 %. Hence, passengers are willing to pay more for comfort.
Which option most seriously strengthens the argument?
A. No new trains were introduced on the same route.
B. The economy grew by 5 % in the same period.
C. A survey shows 70 % travellers are unaware of the fare rise.
D. The Rajdhani reduced its halts, saving 45 min. -
(Easy)
Passage: Every loco pilot who has completed 1000 hours of electric-loco driving is promoted to A-grade. Ramesh has just completed 1000 such hours.
Conclusion: Ramesh will be promoted to A-grade.
The argument assumes that
A. Ramesh has no disciplinary case pending
B. electric-loco hours are countable
C. A-grade is the highest grade
D. promotions are annual -
(Medium)
Passage: After installing LED lights in all coaches, power consumption per coach fell by 20 %. Therefore, if all 50 000 coaches are converted, the Railways will save ₹400 crore annually.
The argument is most vulnerable to criticism on the grounds that it
A. ignores the cost of LED installation
B. assumes the 20 % saving scales linearly
C. forgets that coaches also use diesel
D. underestimates passenger comfort -
(Hard)
Passage: A study shows that stations with more foot over-bridges (FOB) have fewer stampede deaths. Hence, the Ministry should build more FOBs at all stations.
Which option reveals the flaw in the reasoning?
A. Busy stations already have more FOBs because they have more passengers.
B. FOBs are expensive to maintain.
C. Stampedes can occur on platforms too.
D. escalators are safer than FOBs. -
(Easy)
Passage: Only those who pass the Psycho test can become loco pilots. Anita has not passed the Psycho test.
Conclusion: Anita cannot become a loco pilot.
The reasoning is
A. valid
B. invalid – denies the antecedent
C. invalid – affirms the consequent
D. invalid – undistributed middle -
(Medium)
Passage: In the last 5 years, the number of female RRB candidates has doubled, yet the selection rate has remained 12 %.
Inference: Female candidates are less prepared than males.
The inference is flawed because
A. the total number of male candidates may have risen too
B. 12 % may be higher than the male rate
C. doubling is a percentage increase
D. reservation rules may have changed -
(Hard)
Passage: Whenever the train is late, the controller blames fog. Yesterday the train was late and the controller blamed fog.
Which statement, if true, would most support that the controller was not making an excuse?
A. Meteorological data confirms dense fog at the time.
B. The same controller blamed fog last winter too.
C. The train has never been late in summer.
D. Fog is common in December. -
(Easy)
Passage: All RRB-NTPC toppers use the same mock-test series. Ravi used that series and topped.
The argument commits which fallacy?
A. post hoc ergo propter hoc
B. circular reasoning
C. straw man
D. slippery slope -
(Medium)
Passage: 60 % of Railway accidents are caused by human error; hence, removing humans will remove 60 % of accidents.
The argument assumes that
A. automation is error-free
B. human error is randomly distributed
C. accidents have only one cause
D. technology is cheaper -
(Hard)
Passage: A private operator claims that its semi-high-speed train covers 500 km in 4 h with 95 % punctuality, while the Rajdhani takes 5 h with 80 % punctuality. Hence, the private train is better.
Which option most seriously weakens the claim?
A. The private train skips 6 intermediate stations.
B. The Rajdhani runs at night.
C. Fare of the private train is double.
D. Punctuality is measured differently for both. -
(Easy)
Passage: No chairmen of Railway Board have come from the Traffic cadre since 2015. Mr. Verma, a Traffic officer, wants to become chairman.
Conclusion: Mr. Verma will not become chairman.
The argument is
A. strong inductive
B. weak inductive
C. deductively valid
D. invalid – hasty generalisation -
(Medium)
Passage: After platform tickets were doubled in price, the number of platform tickets sold fell by 30 %. Thus, the measure successfully reduced crowd on platforms.
Which option casts the most doubt on the conclusion?
A. Many people entered using travel tickets instead.
B. The price of rail tickets remained unchanged.
C. Platform ticket revenue rose by 10 %.
D. The number of trains increased. -
(Hard)
Passage: In a survey of 1000 daily passengers, 80 % said they would pay 10 % extra for guaranteed seats. Hence, the Railways can raise fare by 10 % without losing passengers.
The argument is most vulnerable to which criticism?
A. The sample may not be representative of all passengers.
B. 10 % extra may not cover the cost of guarantee.
C. Passengers may change their mind after the increase.
D. All of the above. -
(Easy)
Passage: Only diesel locos can haul the train on the Branch line because the route is not electrified. Train D is running on the Branch line.
Conclusion: Train D is hauled by a diesel loco.
The reasoning is
A. valid
B. invalid – converse error
C. invalid – inverse error
D. invalid – illicit major -
(Medium)
Passage: The number of vacancies in RRB-NTPC 2022 was 20 % lower than in 2021, yet the number of applicants rose by 30 %. Therefore, competition per seat has increased by 50 %.
The calculation assumes that
A. no candidate applied in both years
B. all applicants appear for the exam
C. vacancies are filled in both years
D. the rise is uniformly distributed across categories -
(Hard)
Passage: A safety audit found that stations that hold monthly fire drills have 50 % fewer fire incidents. Hence, monthly drills cause fewer fires.
Which option, if true, most strengthens the causation?
A. Stations with drills have similar infrastructure to those without.
B. The audit was done by an independent agency.
C. Fire incidents are always reported.
D. Drill attendance is compulsory for staff. -
(Easy)
Passage: If the signal is red, the train must stop. The signal is not red.
Conclusion: The train need not stop.
The argument is
A. valid
B. invalid – denying the antecedent
C. invalid – affirming the consequent
D. valid – contrapositive -
(Medium)
Passage: Every train that arrives early is rewarded a green tag. The Shatabdi does not have a green tag.
Which conclusion necessarily follows?
A. The Shatabdi did not arrive early.
B. The Shatabdi arrived late.
C. The Shatabdi broke down.
D. None of the above. -
(Hard)
Passage: A researcher argues that stainless-steel coaches last 35 years while aluminium coaches last 25 years, so stainless-steel is more economical.
Which fact is most crucial to evaluate the argument?
A. Maintenance cost per year of each type
B. Colour of stainless steel
C. Number of coaches Indian Railways owns
D. Weight of aluminium coaches -
(Medium)
Passage: After introducing biometric attendance for gangmen, the productivity of track-repair gangs rose by 15 %. Hence, biometric attendance improves productivity.
The argument would be weakest if which were true?
A. Simultaneously, new power tools were supplied.
B. Biometric machines often fail in rain.
C. Gangmen dislike the new system.
D. Supervisors were changed every month. -
(Easy)
Passage: No RRB exam has ever been postponed due to heat wave. The 2023 exam is scheduled for June.
Conclusion: The 2023 exam will not be postponed due to heat wave.
The argument relies on
A. analogy
B. precedent
C. authority
D. cause-effect
Answers with explanations
-
Answer
Correct: **A. certainly true**.
The statement is a categorical syllogism: All P are Q; R is P; therefore R is Q. Valid deduction.
-
Answer
Correct: **A. A new police booth was opened in 2023.**
Introduces an alternative cause for the drop in theft, weakening the claimed causal link.
-
Answer
Correct: **B. The cost of fencing is disproportionate to lives saved on that stretch.**
The critic’s point is economic; without this assumption the criticism collapses.
-
Answer
Correct: **D. invalid because correlation is not causation**.
The passage gives no evidence that the exam caused high ITI scores.
-
Answer
Correct: **A. No new trains were introduced on the same route.**
Rules out a major alternative explanation for the occupancy rise, strengthening the comfort-premium argument.
-
Answer
Correct: **A. Ramesh has no disciplinary case pending**.
If he has a case, the promotion rule may not apply; hence the assumption is necessary.
-
Answer
Correct: **B. assumes the 20 % saving scales linearly**.
LED savings may plateau; linear projection is the biggest vulnerability.
-
Answer
Correct: **A. Busy stations already have more FOBs because they have more passengers.**
Reverses the causality—exposes the flaw.
-
Answer
Correct: **A. valid**.
Denies the consequent: Only if P then Q; not Q; therefore not P. Valid contrapositive.
-
Answer
Correct: **A. the total number of male candidates may have risen too**.
Selection rate is a ratio; without male numbers the comparison is impossible.
-
Answer
Correct: **A. Meteorological data confirms dense fog at the time.**
Provides independent evidence for fog, supporting that the controller cited a real cause, not an excuse.
-
Answer
Correct: **A. post hoc ergo propter hoc**.
Assumes that because topper used the mocks, the mocks caused the success.
-
Answer
Correct: **A. automation is error-free**.
If automation also errs, the 60 % reduction claim fails.
-
Answer
Correct: **D. Punctuality is measured differently for both.**
Undermines the very comparability of the 95 % vs 80 % figures.
-
Answer
Correct: **B. weak inductive**.
A 7-year trend is too small to guarantee future outcome; inductive strength is low.
-
Answer
Correct: **A. Many people entered using travel tickets instead.**
Suggests crowd merely shifted, not reduced.
-
Answer
Correct: **D. All of the above**.
Each choice highlights a different vulnerability—sample bias, cost, or attitude change.
-
Answer
Correct: **A. valid**.
Direct application of the given conditional rule.
-
Answer
Correct: **A. no candidate applied in both years**.
Ensures the applicant pools are distinct, required for the 50 % calculation.
-
Answer
Correct: **A. Stations with drills have similar infrastructure to those without.**
Eliminates the confounding variable of infrastructure quality, strengthening causation.
-
Answer
Correct: **B. invalid – denying the antecedent**.
“Must stop only if red” does not imply “need not stop if not red”; other stop-signals may exist.
-
Answer
Correct: **A. The Shatabdi did not arrive early.**
Contrapositive of the reward rule; “late” is stronger than we know.
-
Answer
Correct: **A. Maintenance cost per year of each type**.
Economics depends on total cost, not just life-span.
-
Answer
Correct: **A. Simultaneously, new power tools were supplied.**
Provides an alternative cause for the productivity rise, undermining the biometric claim.
-
Answer
Correct: **B. precedent**.
The reasoning relies on historical pattern to predict the future.
Shortcuts & Tips
- Filter first: Read question stem → decide task (weaken / assumption / inference) → then read passage.
- Flag extreme words: “only”, “always”, “never”, “must” usually signal invalid assumptions.
- 10-second diagram: For categorical syllogisms, draw Venn circles to check validity in your head.
- Alternative cause hunt: In weakeners, scan for “another reason” that could produce the same outcome.
- Numerical traps: Percentages versus absolute numbers—convert both to the same base before comparing.
- Negation test for assumptions: Negate the choice; if the argument collapses, that’s the necessary assumption.
- Time guard: Cap each CR question at 75 s in mock tests; mark and move, return later if time permits.
BETA
