Quantitative Aptitude
Quantitative Aptitude in IBPS PO covers simplification and approximation, number series, quadratic equations, arithmetic word problems and data interpretation. DI is usually the scoring core, while arithmetic tests ratio, percentage, time-work, speed-distance, interest, mixtures and partnerships.
Core rules
- Percentage change = (new − old)/old × 100; percentage points are absolute differences, not relative changes.
- In ratio chains, make the common term equal: if A:B = 2:3 and B:C = 4:5, use B = 12 to get A:B:C = 8:12:15.
- For work, take total work as the LCM of days; efficiency = total work ÷ days.
- In DI, read units and years before calculating; use approximation only when options are far apart.
Worked example
A completes a job in 12 days and B in 18 days. Together: take total work = LCM(12,18) = 36 units. A does 3 units/day, B does 2 units/day; combined = 5 units/day. Time = 36 ÷ 5 = 7.2 days, i.e. 7 days 4.8 hours (or 7⅕ days). The LCM method avoids fractions and exposes each worker's rate.
Traps
Do not confuse simple and compound interest; CI compounds each period, SI does not. In speed problems, convert km/h to m/s by ×5/18. In mixtures, track the solute, not just total volume. In number series, check differences, ratios and squares before assuming a wrong-term pattern.