Analytical Ability, Reasoning and Quantitative Aptitude
What this domain tests
Number series, coding-decoding, blood relations, syllogisms, seating arrangement, data interpretation and arithmetic on ratio, percentage, time-work, average and mixtures. The food-safety flavour appears in mixture and dilution items, so practise alligation rather than only abstract algebra.
Fast techniques
- Alligation for two-component mixtures: quantities are inversely proportional to differences from the mean.
- Percentage change chains: successive changes multiply, never add.
- Series: check differences, then ratios, then the pattern of added constants.
- Syllogisms: draw the minimum possible Venn diagram; a conclusion is valid only if it holds in every diagram.
Worked example (mixtures)
How should milk at 3.5 per cent fat be blended with cream at 20 per cent fat to give 6 per cent fat milk? Alligation: milk : cream = (20 − 6) : (6 − 3.5) = 14 : 2.5 = 28 : 5. So 28 litres of milk to 5 litres of cream. The logic is that each component's deviation from the target fixes its share.
Worked example (series)
3, 7, 16, 35, 74, ? - the rule is x2 +1, x2 +2, x2 +3, x2 +4, so the next is 74 x 2 + 5 = 153. Always test a doubling-plus-constant rule before assuming a simple difference series.
Traps
- Reading "at least" as "exactly" in inequalities and syllogisms.
- Forgetting to convert litres to millilitres or per cent to fraction.
- Adding successive percentage changes instead of multiplying them.
- In data interpretation, using row totals when the question asks for a column share.
- Rounding intermediate values and then choosing an option that is off by one unit.