Quantitative Aptitude / Numerical Ability for ESIC MTS
What this domain tests
Quantitative Aptitude / Numerical Ability tests arithmetic speed and accuracy: simplification, number system, percentage, ratio and proportion, average, profit and loss, simple and compound interest, time-work, time-speed-distance, and mensuration. ESIC MTS questions are usually direct, so getting the first step right matters more than advanced shortcuts.
Core rules
- Percentage change is calculated on the original base.
- Profit% and loss% are calculated on cost price; discount% is calculated on marked price.
- For successive percentage changes, use net = a + b + ab/100 with the correct signs.
- Time and work: add rates (1/a + 1/b); never add days directly.
- Average = total sum ÷ number of observations; if every value changes by k, the average changes by k.
Worked example
A shopkeeper marks an article 25% above cost and allows a 10% discount. Let CP = ₹100. Then MP = ₹125 and SP = 125 × 0.90 = ₹112.50. Profit = ₹12.50, so profit% = 12.5%. A common wrong answer is 15%, obtained by subtracting 10 from 25; that ignores the different bases.
Traps that cost marks
Using marked price instead of cost price for profit; adding completion times in work problems; forgetting unit conversion in speed questions; rounding too early; treating compound interest as simple interest for more than one year.