Reasoning, Aptitude and Quantitative Ability
This domain tests verbal and non-verbal reasoning plus arithmetic aptitude: series, coding-decoding, blood relations, syllogisms, puzzles, percentages, ratio and proportion, time and work, speed and distance, averages, interest, and mensuration. Speed comes from choosing the shortest valid method.
Core rules
- Percentage change = (new − old)/old × 100; successive changes multiply, they do not add.
- Work rate adds: if A finishes in a days and B in b days, together they take ab/(a + b) days.
- Relative speed adds for opposite directions and subtracts for the same direction.
- Average speed for equal distances is the harmonic mean, 2xy/(x + y).
- In syllogisms, draw Venn diagrams and test only what must follow.
- In coding, map letter positions A = 1 to Z = 26 and check shifts.
Worked example. A can finish a job in 12 days and B in 18 days. A's one-day work is 1/12 and B's is 1/18. Together: 1/12 + 1/18 = 3/36 + 2/36 = 5/36. Time = 36/5 = 7.2 days. The answer is less than either individual time, which is a useful sanity check.
Traps. Do not add successive percentage discounts; do not average speeds arithmetically over equal distances; in blood relations, track gender and generation separately; in syllogisms, a possible conclusion is not a definite one; check units in speed and time problems.