Common reasoning mistakes in IBPS Clerk and how to stop them

Look at the reasoning questions you got wrong in your last three mocks. Very few will be questions you had no idea how to solve. Most will be questions you solved and got wrong: a left that should have been a right, a "some" read as "all", a person given a gender the question never mentioned.

That is good news. A knowledge gap takes weeks to close. A repeat slip can be fixed in days, once you can name it. With a quarter-mark penalty on every wrong answer, each fixed slip earns you back more than the question itself.

Why the same mistakes repeat

Under a sectional timer, your brain takes shortcuts. It reads "facing south" and keeps drawing as if everyone faces north. It sees "all roses are flowers" and answers from what it knows about roses. Shortcuts are fast, which is why they survive. The fix is not to slow everything down. It is to build one small check into each topic, at the exact step where your shortcut fires.

Mistakes by topic

Seating: left and right when facing south

Five people sit in a row facing south. A sits to the immediate right of B.

Someone facing south has their right hand towards the west. If you draw the row with north at the top of the page, west is on your left. So on paper, A appears to the left of B. The common mistake is drawing A on the right of the page.

Fix: draw a small arrow above each seat showing which way that person faces, and turn your own head in that direction before placing anyone. In a circle facing the centre, right is anticlockwise.

Syllogism: answering from real life

Statements: All roses are flowers. Some flowers are red.

Conclusion: Some roses are red.

In real life, some roses are red. From these statements, it does not follow. The red flowers could all be flowers that are not roses. The reverse trap also exists: "All mobiles are laptops. All laptops are tablets" gives "All mobiles are tablets", which follows even though it is false in life.

Fix: judge only from the statements. Draw the diagram with the least overlap the statements allow, and ask whether the conclusion is still true.

Inequality: joining signs that point different ways

Statement: A > B ≥ C < D

Conclusion: A > D

The chain changes direction at C. A and D are both bigger than C, but nothing compares them with each other. No relation can be drawn between A and D, or between B and D.

Fix: trace the path between the two letters. If the signs along it do not all point the same way, the conclusion cannot follow.

Blood relations: guessing gender

P is the sibling of Q. Q is the father of R. How is P related to R?

P is R's uncle or aunt. The question never says whether P is male or female, so "uncle" alone is not a safe answer. Pick "uncle or aunt" if it is offered, otherwise "cannot be determined".

Fix: mark gender in your tree only from words like son, sister, father or wife. Never from a name.

Direction: turning from south or west

A person faces south and turns right. Which way do they face now?

When you face south, your right hand points west. So they face west. The common mistake is east, because on paper "right" feels like "towards the right edge".

Fix: a right turn is always 90° clockwise, whatever the starting direction. North → east → south → west → north.

Ranking: dropping the +1 or −1

K is 12th from the left and 9th from the right. How many people are in the row?

Total = 12 + 9 − 1 = 20. K is counted from both ends, so K is counted twice. The common wrong answer is 21.

Fix: say the reason, "counted twice", every time you write the −1. The order and ranking guide has the full formula set.

Alphanumeric series: counting from the wrong end

In the series 7 K 3 M # 9 P @ 2 R, which element is 4th from the right?

Count R as 1, then 2, then @, then P as 4th. The mistake is to count four places away from R and land on 9.

Fix: the end element is position 1, not position 0.

Coding: trusting the first letter

In a code, BANK is written CZOJ. How is LOAN written?

B → C is +1, but A → Z is −1, N → O is +1 and K → J is −1. The rule alternates +1 and −1. So L → M, O → N, A → B, N → M: MNBM. A candidate who checks only the first letter writes MPBO.

Fix: confirm the rule on every letter before you code the new word.

Data sufficiency: borrowing from the other statement

In a class of 30, what is Q's rank from the top? I. Q is 11th from the bottom. II. R is five ranks above Q.

Statement I alone gives 30 + 1 − 11 = 20th. I alone is sufficient. A candidate who glanced at II while testing I may pick "both together", which is wrong.

Fix: cover the other statement with your hand while you test each one alone.

Summary table

Exam-hall mistakes

• Starting with the first puzzle on screen because it is first, not because it is easiest.
• Guessing in a puzzle set you did not solve. Five wrong answers cost 1.25 marks in the prelims.
• Changing answers at the end without a clear reason.
• Not marking skipped questions, then forgetting to return.

A mistake log

Keep this after every mock:

After five mocks, read the log. If the same mistake appears three times, it becomes your warm-up for the next week.

Spot the mistake

Each line shows a candidate's answer. Find what went wrong.

1. "M faces west and turns left." The candidate writes: M now faces north.
2. "Some apples are red. All red things are costly." The candidate marks "All apples are costly" as following.
3. "X ≥ Y > Z." The candidate says "X > Z" does not follow because of the ≥ sign.
4. "R is the mother of S. S is the brother of T." The candidate says T is R's son.
5. "K is 7th from the left and 7th from the right." The candidate writes 14 people.

Answers:

1. Should be south. Facing west, the left hand points south.
2. Only "Some apples are costly" follows. Only the apples that are red are known to be costly.
3. It does follow. X ≥ Y and Y > Z point the same way, and one strict sign in the chain makes X > Z.
4. T is R's child. T's gender is not given.
5. 13. 7 + 7 − 1.

What to do next

• Go through your last three mocks and sort every wrong reasoning answer into "did not know" or "slipped".
• Start the mistake log today and fill it after every mock.
• Before each mock, do a five-minute warm-up: two inequalities, two syllogisms and one direction question.
• Read the reasoning revision sheet before your next full test.