Critical reasoning for IBPS PO mains

Critical reasoning questions give you a short passage, usually an argument or a plan, and ask what supports it, what hurts it, or what it quietly takes for granted. There is no calculation, and the passages are short. Yet these questions eat time, because two options often look right.

The way through is to stop reading the passage as information and start reading it as an argument: a claim, the reason given for it, and the gap between them. Almost every correct answer lives in that gap.

Read the argument in three steps

1. Find the claim. It is the conclusion or the plan: "so the bank should…", "this shows that…", "the council will…".
2. Find the support. It is the reason offered: a figure, an observation, a past result.
3. Name the gap. Ask what else must be true for the support to lead to the claim. Write the gap in six or seven words in your rough sheet.

Most arguments in these questions have one of three gaps:

• Cause and correlation: two things happened together, and the argument says one caused the other.
• Plan and outcome: a plan is proposed, and the argument assumes it will work.
• Sample and whole: something true of one group is claimed for a larger group.

What each question type asks

Worked example 1: assumption

A state transport corporation will replace 200 diesel buses with electric buses on its busiest routes to cut its running costs.

• Claim: the plan will cut running costs. Support: none stated beyond the switch itself. Gap: electric buses must be cheaper to run.
• Options: (a) Electric buses are cheaper to buy than diesel buses. (b) Passengers prefer electric buses. (c) Over their working life, electric buses cost less per kilometre in energy and maintenance than diesel buses.
• Answer (c). Negate it: if electric buses cost more per kilometre to run, the plan cannot cut running costs. (a) is about purchase price, which the claim does not mention. (b) is outside the argument.

Worked example 2: strengthen

A district began sending text-message reminders to parents before each child's vaccination date. In the next year, more children completed the full schedule on time. The health department credits the reminders.

• Gap: something else might explain the rise.
• Options: (a) In a similar neighbouring district without reminders, completion stayed the same that year. (b) Many parents in the district own mobile phones. (c) The reminders were sent in two languages.
• Answer (a). It rules out a region-wide cause, which makes the reminders the more likely reason. (b) is needed for the plan to work, but it does not show that the plan did work.

Worked example 3: weaken

An online test-series platform reports that students who take its daily quiz score higher in full mock tests than students who do not. It concludes that the daily quiz improves mock scores.

• Gap: the students who choose the quiz may differ in other ways.
• Options: (a) The quiz takes only ten minutes. (b) Students who take the daily quiz also study, on average, many more hours a week than those who do not. (c) The platform plans to add more quiz questions.
• Answer (b). Extra study hours could explain the higher scores on their own. This is the classic weakener: another cause for the same result.

Worked example 4: inference

A cooperative bank's gold-loan disbursements doubled this year, while its personal-loan disbursements fell. The bank did not change the interest rate on either product.

• Options: (a) Gold prices rose this year. (b) Customers now prefer gold loans to personal loans at every bank. (c) The rise in gold loans was not caused by a change in the bank's gold-loan interest rate.
• Answer (c). The passage says the rates did not change, so a rate change cannot be the cause. (a) may be true but is not in the passage. (b) goes beyond this bank.

Worked example 5: cause and effect

• Statement I: Several ATMs in a town ran out of cash over a long weekend.
• Statement II: Banks in the town were closed for three consecutive days.

Answer: II is the cause and I is its effect. With branches shut, the ATMs could not be refilled on the usual schedule and demand kept drawing them down. The reverse makes no sense: empty ATMs do not close banks.

Typical options in this type: I is the cause and II the effect; II is the cause and I the effect; both are independent causes; both are effects of independent causes; both are effects of a common cause. Read all five before choosing.

Traps in the options

• Too extreme: "all", "always", "never", "only" in an option usually go beyond what an argument needs.
• Out of scope: new topics, other countries, other years, other products.
• Restating the claim: an option that repeats the conclusion does not strengthen it.
• True but irrelevant: a fact that may well be correct but does not touch the gap.
• Reversed direction: a weakener offered as a strengthener, or the other way round. Re-read the question stem before you choose.

Practice set

Questions 1 to 3 are based on this passage.

A municipal corporation installed bins with QR codes in ten wards. Residents can scan a code to report an overflowing bin. In the following six months, garbage complaints registered on the corporation's helpline fell by 40% in these wards. The corporation concludes that the QR bins have made these wards cleaner.

1. Which option most weakens the conclusion? (a) The QR bins cost more than ordinary bins. (b) Some residents in the ten wards do not have smartphones. (c) Reports made by scanning the QR codes are not counted as helpline complaints.
2. Which option most strengthens the conclusion? (a) The corporation plans to install QR bins in more wards. (b) Independent cleanliness inspections scored the ten wards higher after the bins were installed, while other wards scored the same. (c) Residents said the QR codes were easy to scan.
3. What does the conclusion assume? (a) Helpline complaint numbers reflect how clean a ward actually is. (b) Every resident uses the QR codes. (c) The helpline is open all day.
4. An online grocery company plans to open small warehouses within two kilometres of dense housing areas so that it can deliver in 15 minutes and win customers away from local shops. Which is an assumption of the plan? (a) Local shops will close within a year. (b) The company already has warehouses in every city. (c) Enough customers value very fast delivery over what local shops offer.
5. In question 4's passage, which option most weakens the plan? (a) Local shops in these areas already deliver phone orders within 15 minutes at no extra charge. (b) The warehouses will stock over 5,000 items. (c) The company raised new funding last year.
6. Statement I: Tomato prices in a city's markets tripled within two weeks. Statement II: Heavy rain destroyed standing crops in the main supplying districts. Which is the cause?
7. Every branch of a bank that installed passbook-printing kiosks reported shorter counter queues. Some branches without kiosks also reported shorter queues. Which must be true? (a) Kiosks were the only reason queues fell. (b) Something other than kiosks shortened queues in at least some branches. (c) Kiosks made queues longer.

Answers

1. (c). If QR reports are counted separately, complaints did not fall; they moved to another channel. The drop in helpline numbers says nothing about cleanliness.
2. (b). An independent measure of cleanliness rose only where the bins were installed, which ties the bins to cleaner wards.
3. (a). The conclusion jumps from fewer complaints to cleaner wards. Negate (a) and the evidence stops meaning anything.
4. (c). The plan only wins customers if speed matters to them more than the shops' advantages. (a) is too extreme; (b) is out of scope.
5. (a). If local shops already offer the same speed at no charge, the company's advantage disappears.
6. II is the cause and I the effect. Lost supply from the growing districts pushes prices up.
7. (b). Queues fell in branches without kiosks, so some other cause was at work there. (a) contradicts that fact; (c) contradicts the first sentence.

What to do next

• For every practice passage, write the claim, the support and the gap in one line each before reading the options.
• Practise the negation test on ten assumption questions this week.
• Move on to statement and assumption questions, which use the same gap-finding skill, and revise the mains reasoning guide for where critical reasoning fits.