General Aptitude and Reasoning: Speed with Accuracy
Core concepts to master
Quantitative aptitude covers percentages, ratio and proportion, averages, profit and loss, simple and compound interest, time–speed–distance, time and work, and mixtures. Reasoning splits into verbal (analogies, odd-one-out, coding–decoding, blood relations, syllogisms) and non-verbal (series, mirror images, paper folding, figure counting). Data interpretation tests table and chart reading. The real skill is recognising the question type within seconds and applying a standard shortcut.
Traps examiners set
- Percentage change measured from the wrong base value.
- Profit calculated on selling price instead of cost price.
- In time and work, adding times instead of adding rates.
- Over-reading a syllogism: only the stated premises count, not real-world knowledge.
- Coding questions where the shift is positional rather than alphabetical.
Rule of thumb
Convert percentages to fractions (25% = ¼, 12.5% = ⅛) to turn awkward multiplication into cancellation. For work problems, let total work equal the LCM of the given days.
Worked example
A can finish a job in 12 days and B in 18 days. Working together, how long do they take?
Use LCM = 36 units of work. A does 3 units/day, B does 2 units/day, together 5 units/day. Time = 36/5 = 7.2 days.
Practice habit
Do a timed set daily and log every error by category; repeated categories reveal the shortcut you are missing.