Quantitative Aptitude and Reasoning
Quantitative Aptitude and Reasoning
This domain measures numerical fluency and structured thinking under time pressure. Quant questions cluster around percentages, ratio and proportion, averages, time-speed-distance, time and work, simple and compound interest, mixtures, and data interpretation from tables and charts. Reasoning covers syllogisms, seating arrangements, blood relations, coding-decoding, series, inequalities, and multi-condition puzzles.
Core rules
- Percentage change is always calculated on the base; successive changes multiply as factors, not add.
- For two years, the CI–SI difference is P(r/100)².
- In ratio problems, keep the same base and convert all quantities to a common unit.
- Time and work: use rates (1/time) and add rates for simultaneous work.
- Syllogism: draw minimal Venn diagrams; do not assume existence unless stated.
- Seating: fix one anchor, then place left and right relative to facing direction.
Worked example
A trader marks goods 40% above cost and offers a 25% discount. What is the profit? Let cost = 100. Marked price = 140. Selling price = 140 × 0.75 = 105. Profit = 5%. The trap is to subtract 25% from 40% and claim 15%; successive percentage changes must be multiplied as factors.
Traps
Percentage points are not percentages. In data interpretation, read units (lakh, crore, thousand) before calculating. In circular seating, left and right reverse for people facing outward. In syllogisms, 'some A are B' converts to 'some B are A'; the invalid move is concluding 'some A are not B'. Do not round intermediate values so aggressively that the final option changes.