Mental Ability and Reasoning: Find the Rule
The Mental Ability and Reasoning section tests process, not syllabus content. You are handed patterns and rules you have never seen and must identify the rule quickly and apply it without arithmetic slips.
Core question types
- Series: number series (differences, x n plus c, squares/cubes, interleaved pairs) and letter series. Anchor the alphabet with EJOTY: E=5, J=10, O=15, T=20, Y=25.
- Coding-decoding: alphabet shifts, reversal, position arithmetic.
- Blood relations, direction sense, ranking, seating arrangements - always draw, never track in your head.
- Syllogisms, Venn diagrams, classification (odd one out), analogies.
- Non-verbal items: series, mirror and water images, paper folding and cutting, embedded figures.
Worked example
Find the next term: 3, 7, 15, 31, ?. Verify a candidate rule against every given term, not just the first pair. The first differences are 4, 8, 16, which points to a doubling rule rather than a constant addition. Test x2 + 1: 3 gives 7, 7 gives 15, 15 gives 31. So the next term is 31 x 2 + 1 = 63.
Traps that cost marks
- Two series interleaved and disguised as one.
- Turn problems: someone facing south who turns left moves east on the page; resolve turns relative to the facing direction.
- Syllogism conclusions that are only possible, when the stem demands what definitely follows.
- Counting a relation from the wrong person: my mother's brother's son is my cousin, not my brother.