Reasoning Ability
Question families
Reasoning Ability tests puzzles and seating arrangements, syllogism, inequality, coding-decoding, blood relations, direction sense, order-ranking, series and input-output. Puzzles carry high marks but consume time; inequality and syllogism are quick scoring.
Method rules
- Syllogism: draw minimal Venn diagrams; a conclusion is valid only if it is true in every diagram consistent with the statements.
- 'Some A are B' is reversible; 'All A are B' is not.
- Inequality: decode chains left to right; '≥' means greater than or equal to, so a conclusion using '>' is not automatically true.
- Coding: compare the code words with the original words, match repeated letters, and identify shift or substitution patterns.
- Blood relations: draw a family tree and mark gender only where stated.
- Seating: fix the definite clue first; use 'facing north/south' to reverse left and right.
Worked example
Statements: All pens are books. Some books are red. Candidate conclusion: Some pens are red. Reasoning: the 'some books' that are red need not include any pen. A Venn diagram with pens inside books and red overlapping only the book region outside pens satisfies both statements and makes the conclusion false. Hence the conclusion does not follow. The valid conclusion is 'Some books are pens', which is the conversion of 'All pens are books'.
Traps
Assuming a possibility conclusion is definite; reversing 'All A are B' into 'All B are A'; ignoring 'only a few' and 'no' statements; and adding information not given in a puzzle. In inequality, do not treat '≥' as '='.