Mathematics and Quantitative Aptitude
What this section tests
Arithmetic and elementary aptitude: percentages, ratio and proportion, averages, profit and loss, simple and compound interest, speed–distance–time, work and pipes, mensuration of simple shapes, LCM and HCF, and basic algebra.
Formula anchors
- Speed = distance ÷ time. Convert km/h to m/s by multiplying by 5/18; convert m/s to km/h by multiplying by 18/5.
- Profit % = (profit ÷ cost price) × 100 - always on cost price, never on selling price.
- Simple interest = P × R × T ÷ 100.
- Average = sum ÷ count; if every value in a set rises by k, the average rises by k.
Worked example (speed)
A man covers 600 m in 2 minutes. Find his speed in km/h. Step 1 - convert time to seconds: 2 min = 120 s. Step 2 - speed = 600 ÷ 120 = 5 m/s. Step 3 - convert: 5 × 18/5 = 18 km/h. The mark-losing errors are stopping at 5 m/s, or dividing 600 by 2 and reporting an absurd 300 km/h.
Worked example (percentage)
A jacket priced at Rs 2,400 is discounted 15%. Discount = 0.15 × 2400 = Rs 360, so the price paid is Rs 2,040. Always apply the discount to the marked price, not to an already reduced price.
Traps
- Confusing “per cent of” with “per cent more than”.
- Ratio problems where the total changes after someone enters or leaves - rebalance the whole total, not just one share.
- Approximation is fine, but the options are usually built around one careless slip, so redo the final line of arithmetic.