Quantitative Aptitude / Basic Mathematics
Quantitative Aptitude tests numerical fluency in percentage, ratio, average, interest, profit and loss, time-work, speed-distance and mensuration. Most questions are built from a small set of formulas, so accuracy in the base value matters more than speed.
Core formulas
- Percentage change = (change ÷ original) × 100.
- Profit% = (SP − CP)/CP × 100; discount% is always on marked price.
- SI = PRT/100; CI = P(1 + R/100)^T − P.
- Average = sum ÷ count; combined averages require weighted sums.
- Work: if A does a job in x days, one day's work = 1/x.
- Speed = distance/time; 1 km/h = 5/18 m/s.
Worked example
A shopkeeper marks an article 40% above cost and allows a 25% discount. Find profit%. Let CP = 100. MP = 140. SP = 140 × 75/100 = 105. Profit = 105 − 100 = 5, so profit% = 5/100 × 100 = 5%.
Traps
- Applying discount to cost price instead of marked price.
- Using the new value as the base for a percentage change.
- Mixing simple and compound interest for more than one year.
- Averaging averages without weighting by group size.
- In time-work, adding days instead of adding rates.
- Using diameter where radius is required in mensuration.