Reasoning / Mental Ability for TNUSRB Constable
Reasoning tests number and letter series, coding-decoding, blood relations, direction sense, analogy, odd-one-out, syllogism, ranking and seating, plus clock and calendar questions. Each type has a fixed method, so the marks come from recognising the pattern quickly.
Core methods
- Number series: test differences first, then ratios, then squares and cubes, then alternating or two-tier patterns.
- Blood relations: draw a family tree; mark males and females separately and use vertical lines only for parent-child links.
- Direction sense: fix north at the top, then track the facing after every turn - a right turn from north faces east, and a right turn from east faces south.
- Syllogism: a conclusion follows only if it is true in every possible diagram, not just one.
Worked example
A man walks 8 km north, turns right and walks 6 km, then turns right again and walks 8 km. How far is he from the start? Trace the position: 8 km north gives (0, 8). A right turn from north faces east, so 6 km takes him to (6, 8). A right turn from east faces south, so 8 km brings him to (6, 0). He is 6 km due east of the starting point.
Traps that cost marks
Assuming every right turn is towards the east - it depends on the direction being faced. In blood relations, mixing up a maternal uncle with a father's brother. In syllogism, answering from real-world knowledge instead of the given statements. For clocks, the angle is |30H − 5.5M|, so at 3:40 it is 130°, not 140°.