Quantitative Aptitude / Numerical Ability
Quantitative Aptitude / Numerical Ability
The section tests speed and accuracy on percentage, ratio and proportion, average, profit and loss, simple and compound interest, time-work, speed-distance, mixtures, number series, simplification/approximation, and data interpretation (tables, bar and pie charts). The J&K Bank Associate level favours direct application over lengthy algebra, so converting words into one clean equation is the main skill.
Rules to keep ready
- Percentage change is always calculated on the original/base value. A 20% increase followed by a 20% decrease gives a net 4% decrease, because 1.2 × 0.8 = 0.96.
- For compound interest, amount = P(1 + r/100)^n; for simple interest, SI = PRT/100. Never use the SI formula when the question says "compounded annually".
- Time and work is inversely proportional to rate: if A does a job in 12 days and B in 18 days, together they do 1/12 + 1/18 = 5/36 per day, so 36/5 = 7.2 days.
- Average speed for equal distances is the harmonic mean, 2xy/(x+y), not (x+y)/2.
Worked example
A sum becomes ₹9,680 in 2 years at 10% per annum compound interest. Find the principal.
Amount = P(1.1)^2 = 1.21P. So P = 9680 / 1.21 = ₹8,000. Check: 8000 → 8800 after year 1 → 9680 after year 2. The trap answer ₹8,066 comes from using simple interest, 9680 × 100/(100 + 20).
Traps
- Mixing percentage points with percent change.
- In data interpretation, missing "in lakh" or "in thousand" in the axis label.
- In number series, forcing one pattern when two alternating patterns are present.
- In approximation, rounding a denominator down and still choosing the exact option.