Quantitative Ability
Quantitative Ability
ATMA's Quantitative Ability section tests numerical reasoning across arithmetic, algebra, geometry, mensuration, and data interpretation. Most items are solvable by converting the wording into one or two equations, so the marks come from setting up cleanly rather than from long calculation.
Core rules
- Use multipliers for percentage change: a 40% increase is x1.40; a 25% discount is x0.75. Successive changes multiply, not add.
- In ratio problems, assign a common multiplier k and keep all quantities in the same unit.
- For time and work, add rates: if A finishes in a days and B in b days, together they finish in ab/(a+b) days.
- For speed, keep distance, speed, and time in matching units; convert minutes to hours before substituting.
- In data interpretation, read the axis labels and units before comparing values; approximation is acceptable only when options are far apart.
Worked example
A can complete a task in 12 days and B in 18 days. Working together, how long will they take?
A's rate is 1/12 of the task per day; B's rate is 1/18. Combined rate = 1/12 + 1/18 = 3/36 + 2/36 = 5/36. Time = 1 divided by (5/36) = 36/5 = 7.2 days. The answer is 7.2 days, or 7 days 4.8 hours if the options use mixed units.
Traps
- Applying a discount to the cost price instead of the marked price.
- Adding percentage changes directly: 40% up then 25% down is not 15% up.
- Forgetting that work rates add while times do not.
- Leaving units mixed in speed or mensuration problems.
- Choosing the first computed number without checking what the question asks.