Reasoning and Logical Deduction
Reasoning and Logical Deduction
This domain tests pattern recognition and rule-based deduction without heavy computation. Typical question types are number and alphabet series, coding–decoding, blood relations, direction sense, syllogisms, seating and arrangement puzzles, analogies, odd-one-out classification, and clocks or calendars.
Core rules
- Series: check differences first, then ratios, then alternating, square or cube patterns. For alphabet series, convert letters to positions (A = 1 … Z = 26).
- Coding–decoding: write the letter positions and look for a constant shift, reversal, or position-wise operation.
- Blood relations: draw a family tree; mark males and females separately and use horizontal lines for siblings and spouses.
- Direction sense: sketch the path. Net displacement after right-angle turns is found with Pythagoras.
- Syllogism: use Venn diagrams. "All A are B" does not permit "All B are A". "Some A are B" does not mean "Some A are not B".
Worked example
Statements: All roses are flowers. Some flowers fade quickly. Conclusion: Some roses fade quickly. Reasoning: Draw flowers as a large circle, roses as a circle inside it, and a "fade quickly" region overlapping flowers. That region need not touch the roses at all, so the conclusion is not guaranteed and does not follow.
Traps that cost marks
- Converting "All A are B" into "All B are A".
- Assuming "some" excludes "all" - in logic, "some" means "at least one".
- Losing track of left and right after a turn when the person faces south.
- In seating puzzles, ignoring a "not" condition or a fixed-position clue.
- In blood relations, treating "only son of my mother" as the speaker rather than the speaker's brother.