Quantitative Aptitude / Numerical Ability for ESIC UDC
Quantitative Aptitude in ESIC UDC tests numerical fluency and multi-step problem solving. Recurring areas are simplification and approximation, number series, percentage, ratio and proportion, average, profit and loss, simple and compound interest, time and work, speed and distance, mensuration, and data interpretation.
Core rules to apply
- Percentage change = (change ÷ original) × 100; successive changes multiply, so a 20% rise then 10% fall gives 1.20 × 0.90 = 1.08, an 8% net rise.
- Profit% and loss% are calculated on cost price unless stated otherwise.
- For time and work, convert days into units of work using the LCM of the given days.
- Speed = distance ÷ time; convert km/h to m/s by multiplying by 5/18.
- In data interpretation, read units, years and headings before calculating.
Worked example
A can finish a task in 12 days and B in 18 days. Working together, how long will they take? Take LCM(12, 18) = 36 units of work. A does 36 ÷ 12 = 3 units/day; B does 36 ÷ 18 = 2 units/day. Together they do 5 units/day, so time = 36 ÷ 5 = 7.2 days, or 7 days 4.8 hours. The reasoning is to convert rates into a common work unit rather than averaging 12 and 18.
Traps that cost marks
- Applying a successive percentage change by simple addition.
- Using selling price instead of cost price as the base for profit percentage.
- Forgetting unit conversion in speed, area and volume questions.
- Rounding too early in approximation questions and missing the nearest option.
- In DI, ignoring "in lakh" or "in thousand" labels and misreading the asked year.