Reasoning and Mental Ability: Rule-Finding Under Time Pressure
Reasoning and Mental Ability tests how quickly you detect a rule: number and letter series, coding-decoding, blood relations, direction sense, ranking, seating arrangements, syllogism, clocks and calendars, dice, mirror and water images, and non-verbal figure series. Every item has one determinable answer; the skill is systematic rule-finding, not memorisation.
Working rules by type
- Series: test differences, then ratios, then alternating, square and cube patterns; convert letters to positions (A=1 to Z=26).
- Coding: compare code word and plain word letter by letter to find the shift, and check for reversal.
- Blood relations: draw a family tree, plus and minus signs for gender, horizontal lines for siblings, vertical for parent-child.
- Direction: fix north at the top and mark each turn; a left turn while facing south means facing east.
- Syllogism: draw the minimum possible Venn diagram; a conclusion is valid only if it holds in every diagram.
- Ranking: total = (rank from left + rank from right) - 1.
Worked example
Statements: All engineers are graduates. Some graduates are singers. Conclusions: I. Some engineers are singers. II. Some singers are graduates. Reasoning: 'some graduates are singers' converts to 'some singers are graduates', so II follows. Those singers may all lie outside the engineer circle, so I need not follow. Answer: only II follows.
Traps that cost marks
- Treating a possibility conclusion ('can be true') as a definite one.
- Reversing 'all A are B' into 'all B are A'; only 'some B are A' is valid.
- In seating puzzles, ignoring the facing direction when applying left and right.
- Clock angle is |30H - 5.5M|; hands coincide 11 times in 12 hours, not 12.
- Counting the starting day twice in calendar questions.