Reasoning and Mental Ability: Pattern Recognition Under Time Limits
High-yield question types
Number and letter series, coding-decoding, blood relations, direction sense, syllogism, seating and ranking, analogy, statement-assumption, plus non-verbal items such as mirror images, embedded figures and paper folding.
Method for each type
- Series: test differences first, then ratios, then squares or cubes, then alternating sub-series in odd and even places.
- Coding: write alphabet positions 1–26 above the letters; test a fixed shift, reversal, or opposite-letter coding (A↔Z, B↔Y; opposite pairs sum to 27).
- Blood relations: draw a family tree; mark gender only where the question states it.
- Direction: sketch the path and fix north before moving; turning left after facing south means facing east.
- Syllogism: use Venn diagrams. "Some A are B" is reversible; "All A are B" is not.
Worked example
Find the next term: 3, 7, 15, 31, ? Differences are 4, 8, 16 - doubling each time, so the next difference is 32 and the term is 31 + 32 = 63. Cross-check with the rule ×2 + 1: 3→7→15→31→63. Both methods agree. Answer: 63.
Traps that cost marks
- Assuming a person's gender from a name instead of the stated relation.
- Treating "some A are B" as also meaning "some B are not A".
- Ignoring the starting direction in two-turn direction questions.
- Choosing the first pattern that fits rather than the one that fits all given terms.