Quantitative Aptitude & Reasoning
What this domain tests
Quantitative Aptitude & Reasoning tests numerical fluency and logical deduction: percentage, ratio, average, profit-loss, SI/CI, time-work, speed-distance, mensuration, number series, coding-decoding, blood relations, direction sense and syllogism.
Core rules
- Percentage change is always on the original base unless stated otherwise; successive changes use a + b + ab/100 (with signs).
- Profit/loss is calculated on cost price; discount is on marked price.
- Work: total work = efficiency × time; combine rates by adding per-day work.
- Speed: distance = speed × time; convert km/h to m/s by multiplying 5/18.
- Average: total = average × number; when a person joins or leaves, adjust the total.
- Reasoning: in syllogism, draw minimal Venn diagrams; in blood relations, use a family tree with gender marks; in series, check difference, ratio and squares/cubes.
Worked example
A trader marks an article 25% above cost and allows 10% discount. Let CP = 100. MP = 125. SP = 125 × 0.90 = 112.5. Profit = 12.5 on CP 100, so profit = 12.5%.
Traps
Do not apply discount to CP; do not use the SI formula for CI; do not assume all numbers in a series are positive; in direction sense, track facing direction after each turn.