Quantitative Aptitude: Pattern Speed, Not Advanced Maths
Quantitative Aptitude rewards fast, clean calculation on familiar patterns rather than advanced mathematics. The paper leans heavily on data interpretation and on arithmetic word problems, so the winning habit is recognising a standard model in the first ten seconds and applying a shortcut instead of a full derivation.
Where the marks are
- Simplification and approximation: BODMAS, surds, and fraction–percentage equivalents such as 12.5% = 1/8, 16⅔% = 1/6, 6.25% = 1/16.
- Number series - missing term and wrong term.
- Quadratic equations and quantity comparison.
- Data interpretation: table, bar, line, pie and caselet, generally three to four sets.
- Arithmetic: percentage, ratio and proportion, average, profit and loss, simple and compound interest, time and work, pipes and cisterns, speed–distance–time, trains, boats, mixtures and alligation, partnership, ages.
Rules worth memorising
- Two successive changes of a% and b% equal a + b + ab/100.
- Time and work: convert days into work-per-day (efficiency = 1/days), then add the efficiencies.
- Compound interest compounded half-yearly means rate ÷ 2 and time × 2.
Worked example
Find the compound interest on ₹8,000 at 10% per annum for 2 years, compounded annually. Effective two-year rate = 10 + 10 + (10 × 10)/100 = 21%. CI = 21% of 8,000 = ₹1,680. Long-route check: 8,000 → 8,800 → 9,680, so interest = 9,680 − 8,000 = ₹1,680.
Traps that cost marks
Taking a percentage on the wrong base (profit on cost price, discount on marked price); in DI, comparing a value with a total that already includes it; forgetting to convert minutes into hours in speed questions; in pipes and cisterns, treating a leak as positive work; over-rounding in approximation questions so the nearest option is no longer unique.