Quantitative Aptitude
What this section tests
Quantitative Aptitude covers simplification and approximation, number series, quadratic equations, ratio and proportion, time–work, speed–distance, interest, mixtures, probability, and arithmetic-based data interpretation. The Federal Bank PO paper rewards exact calculation and smart shortcuts equally.
Core rules
- Number series: check differences, then ratios, then squares/cubes, then alternating patterns.
- For successive percentage changes, use multipliers: a 20% rise then a 10% fall is 1.20 × 0.90 = 1.08, an 8% net rise.
- Time–work: convert days to one-day work; add rates for people working together.
- SI = PRT/100; CI uses A = P(1 + r/100)^t, so interest = A − P.
- In mixtures, track the quantity of the unchanged component, usually water or pure spirit.
Worked example
A can finish a job in 15 days and B in 20 days. With C, they finish in 6 days. How long would C alone take? A’s rate = 1/15; B’s rate = 1/20. Together with C: 1/6. A + B = 1/15 + 1/20 = 7/60. C’s rate = 1/6 − 7/60 = 10/60 − 7/60 = 3/60 = 1/20. C alone takes 20 days.
Traps that cost marks
Using the new value as the base for percentage change; applying SI formulas to CI; forgetting unit conversions (km/h to m/s: multiply by 5/18); and rounding too early in approximation questions. In DI arithmetic, confirm whether the question asks for a total, a difference, or a ratio.