Reasoning and Mental Ability
Question families
Number, letter and mixed series; analogy; classification; coding-decoding; blood relations; direction sense; syllogism; seating arrangement; order and ranking; clocks, calendars; and non-verbal series.
Core techniques
- Series: test differences first, then ratios, then alternate interleaved series, then squares and cubes with a constant offset.
- Coding: write letter positions (A=1 … Z=26) and look for a fixed shift; check reversal for confusing patterns.
- Blood relations: draw a family tree, marking male and female, and never solve it mentally.
- Syllogism: draw Venn diagrams. A conclusion is valid only if it holds in every possible diagram.
- Direction: fix north at the top and treat a right turn as clockwise.
Worked example
“If CAT is coded 3120, what is DOG?” Reasoning: C = 3, A = 1, T = 20, so the code is simply letter positions written in order. D = 4, O = 15, G = 7, giving 4157. Always test the proposed rule against all letters of the given word before applying it.
Traps that cost marks
- Assuming one pattern when two alternate series are interleaved.
- In blood relations, forgetting that “my father’s only son” may be the speaker himself.
- In syllogism, converting “all A are B” into “all B are A”, which is invalid.
- In direction questions, losing track of left and right after a turn.
- In ranking questions, forgetting to add one when counting between positions.