Reasoning and Logical Ability
What this section tests
Reasoning in this paper is non-verbal-heavy and time-bound: number and letter series, analogy, coding–decoding, blood relations, direction sense, ranking and arrangement, syllogism, Venn diagrams, clock and calendar, dice and cubes, and mirror or water images.
Core rules
- Series: check the difference, then the ratio, then alternating patterns; for letter series, convert letters to positions (A = 1 … Z = 26).
- Coding–decoding: test shift of +1, −1, +2, −2 or reversal before assuming a complex rule.
- Blood relations: draw a small family tree, using + for male and − for female; never solve in your head.
- Ranking: total = position from left + position from right − 1.
- Direction sense: sketch the path; net displacement needs Pythagoras when the path is not straight.
- Syllogism: draw the minimum possible Venn diagram; a conclusion is valid only if it holds in every diagram.
Worked example
Question: Pointing to a photograph, a man says, "She is the daughter of my grandfather's only son." How is she related to him?
Step 1: "My grandfather's only son" - the word "only" rules out uncles, so this is the speaker's father. Step 2: "Daughter of my father" = the speaker's sister (or the speaker herself, but the speaker is male here). Step 3: Answer - sister. The word "only" is doing all the work; without it the answer would be ambiguous.
Traps that cost marks
- Ignoring "only", "not", "all but" qualifiers.
- Solving blood relations without the family tree and reversing a relationship.
- In syllogism, accepting a conclusion that needs an extra assumption.
- Clock problems: the minute hand gains 5.5° per minute over the hour hand.