Quantitative Aptitude
What Quantitative Aptitude tests
IBSAT's Quantitative Aptitude questions cover arithmetic (percentages, profit and loss, simple and compound interest, ratio and proportion, time-speed-distance, time and work, averages, mixtures), elementary algebra, number properties, geometry and mensuration, and basic permutations, combinations, and probability. Most items are solvable by choosing the right shortcut.
Core rules
- Percentage change: Use multipliers. A 25% increase is x1.25; a 25% decrease is x0.75. Successive changes multiply: a 40% rise then a 20% fall gives 1.40 x 0.80 = 1.12, a net 12% rise.
- Profit and loss: Discount is applied to the marked price, not the cost price. Profit percentage is calculated on cost price unless stated otherwise.
- Rates: Add work rates for pipes or workers working together; subtract for leaks or opposing speeds. Convert km/h to m/s by multiplying by 5/18.
- Interest: Simple interest is linear; compound interest compounds each period. Do not use the SI formula for CI.
Worked example
A shopkeeper marks an item 40% above cost and then allows a 25% discount. What is the profit percentage? Take cost = 100. Marked price = 140. Selling price = 140 x 0.75 = 105. Profit = 5 on cost 100, so 5%. A common wrong answer, 15%, comes from subtracting 25 from 40 rather than multiplying.
Traps
Adding percentages that should be multiplied; applying discount to cost price; mixing units in speed or mensuration; using the wrong base for profit percentage.