Quantitative Aptitude
JEMAT's Quantitative Aptitude section tests numerical fluency across arithmetic, algebra, geometry, mensuration and data interpretation. Questions are usually short, so marks come from choosing efficient methods rather than long computation.
Core rules and concepts
- Percentage change: successive changes multiply. A 20% rise then a 20% fall gives 0.96 of the original - a net 4% fall, not zero.
- Ratio: if a:b = 2:3, write a = 2k and b = 3k. One variable prevents fraction errors.
- Profit and loss: profit percent is calculated on cost price unless stated; discount percent is calculated on marked price.
- Interest: SI = PRT/100; CI = P[(1 + R/100)^T − 1]. For two years, CI − SI = P(R/100)^2.
- Time, speed and distance: convert km/h to m/s by multiplying by 5/18. Relative speed adds for opposite directions and subtracts for the same direction.
- Data interpretation: read axis labels and units first, then compute only the required value.
Worked example
A shopkeeper marks an article 40% above cost and offers a 25% discount. Find the profit percent. Let CP = 100. Marked price = 140. Selling price = 140 × (1 − 0.25) = 105. Profit = 105 − 100 = 5 on a cost of 100, so profit = 5%.
Traps that cost marks
- Taking the discount on cost price instead of marked price.
- Adding successive percentage changes instead of multiplying factors.
- Mixing minutes and hours, or kilometres and metres, in speed questions.
- Reading a bar chart by visual height when the axis is truncated or non-linear.
- Stopping at x when the question asks for 2x, x + 5, or a ratio.
Approximate in data interpretation only when the answer options are widely spaced; otherwise calculate exactly.