Reasoning, Mental Ability and Quantitative Aptitude
Reasoning, Mental Ability and Quantitative Aptitude
This domain tests numerical ability and logical reasoning: percentages, ratio, average, time and work, speed and distance, series, coding, blood relations, direction sense and syllogism. Speed comes from knowing standard formulas.
Core rules
- Percentage change = (change ÷ original) × 100. A 20% increase is not cancelled by a 20% decrease.
- Average of consecutive numbers equals the middle number.
- Time and work: total work = rate × time; if 5 nurses take 12 days, total work is 60 nurse-days.
- Speed = distance ÷ time; convert km/h to m/s by multiplying by 5/18.
- Series: check differences first, then ratios, then squares and cubes.
- Blood relations: draw a family tree; direction sense: fix the starting point and track turns.
Worked example
Five nurses finish a task in 12 days. How long will six nurses take? Total work = 5 × 12 = 60 nurse-days. Time = 60 ÷ 6 = 10 days. This is inverse proportion: more nurses, fewer days.
Traps
- Use BODMAS strictly; do not add before multiplying.
- Convert units before calculating speed or area.
- In percentage questions, the base changes after the first change.