Logical Reasoning and Analytical Ability
Logical reasoning is marked per question and answers are exact, so this section is the easiest place to bank marks quickly. Question types are number and letter series, analogies, coding-decoding, direction sense, blood relations, syllogisms, seating arrangement and statement-assumption.
Rules that apply
- Series: test first differences, then second differences; test ratios; check whether two interleaved series alternate.
- Coding: convert letters to positions (A = 1 to Z = 26) and look for constant shifts, reversals or position sums.
- Syllogism: 'No A is B' converts to 'No B is A', and 'Some A are B' converts to 'Some B are A'. 'All A are B' does not convert to 'All B are A'.
- Direction: draw north-south and east-west axes; net displacement uses Pythagoras.
- Arrangement: fix the most constrained person or seat first, then fill around it.
Worked example
Series: 3, 6, 11, 18, 27, ? First differences are 3, 5, 7, 9, so the next difference is 11 and the answer is 38. Cross-check with the rule n squared plus 2: 1 + 2 = 3, 4 + 2 = 6, 9 + 2 = 11, 16 + 2 = 18, 25 + 2 = 27, 36 + 2 = 38. Two independent methods giving 38 confirms it; a single method that gives 39 should send you back.
Traps
Reversing 'all' statements. Ignoring the word 'only' in an assumption question - 'only officers may seize' is far stronger than 'officers may seize'. Adding information to a diagram that the premises never supplied. In direction questions, forgetting a final turn back towards the start. Spending four minutes on one arrangement when three series questions could have been solved.