Reasoning, Mental Ability and Quantitative Aptitude
Reasoning and Quantitative Aptitude test pattern recognition and clean arithmetic under time pressure. Topics include series, coding-decoding, blood relations, direction sense, syllogism, seating, percentages, ratio, average, time-work, speed-distance and data interpretation.
Core rules
- Series: check differences, then ratios, squares and cubes, and alternating patterns.
- Coding: convert letters to positions (A=1 ... Z=26) and test shifts.
- Syllogism: draw minimal Venn diagrams; do not assume membership beyond the statements.
- Percentage: successive changes use a + b + ab/100.
- Time-work: add rates (1/time), not times.
- Speed: convert km/h to m/s by multiplying 5/18.
Worked example
A shopkeeper marks an article 25% above cost and allows a 20% discount. Find profit or loss percent. Reasoning: Let CP = 100. MP = 125. Discount is on MP, so SP = 125 × 0.80 = 100. Since SP = CP, there is no profit or loss. Answer: 0%.
Traps
- Taking discount on CP instead of MP.
- Adding successive percentages directly.
- Averaging speeds without weighting by time.
- In syllogism, treating a possibility as a certainty.
- Missing unit changes in ratio and speed questions.
Data interpretation
Approximate first, then compute only the option-relevant value; check whether the question asks for percentage, percentage point or ratio.