Quantitative Aptitude
Domain overview
Quantitative Aptitude in Haryana CET Group D covers simplification, number system, HCF-LCM, percentage, ratio, average, profit-loss, simple and compound interest, time-work, speed-distance, mensuration and data interpretation. The paper is MCQ-based, so approximation and option elimination are legitimate tools.
Core rules and concepts
- Percentage and profit-loss: Always identify the base. Profit% = (SP−CP)/CP × 100; discount is calculated on marked price.
- Ratio: Convert to a common unit before comparing; if a:b = 2:3 and b:c = 4:5, make b common (8:12:15).
- Average: Total = average × number of items; adding a value changes the total, not the count.
- Time-work: Use one-day work = 1/n; combine rates by addition; total time = 1/(sum of rates).
- Mensuration: Keep formulas for circle, triangle, rectangle, cylinder and cube; watch unit conversions.
Worked example
A shopkeeper marks an article 40% above cost and gives 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%. Reasoning: discount applies to MP, not CP; using CP as the discount base gives a wrong answer.
Traps that cost marks
- Calculating discount on cost price instead of marked price.
- Mixing simple and compound interest for multi-year problems.
- Forgetting to convert minutes to hours in speed questions.
- Averaging percentages with different bases.