General Aptitude - Quantitative and Data Interpretation
Quantitative and Data Interpretation tests arithmetic reasoning and the ability to read tables, charts, and short data sets. Topics include percentages, ratios, averages, rates, profit and loss, simple interest, counting, and probability. Questions are usually computational but designed so that estimation and careful reading save time.
Core rules
- Percent change = (new − old) / old × 100. Successive changes multiply: a 20% rise then a 20% fall gives 1.2 × 0.8 = 0.96, a 4% net fall.
- Ratios must use the same units; scale one side before adding.
- Average = total / count, so total = average × count. For combined groups, weight the averages by group size.
- Work rate: work = rate × time; combined rates add, but times do not.
- Data interpretation: read the title, units, and axis labels before calculating. Compute only the quantity asked.
Worked example
A jacket costs 500,000 toman. Its price is increased by 20%, then reduced by 20%. What is the final price? Final = 500,000 × 1.20 × 0.80 = 480,000 toman. This is a 4% decrease, not a return to the original, because the discount is taken on the higher price.
Traps
Adding successive percentages; taking a percentage of the wrong base; averaging averages; ignoring units such as thousands; reading a table's total row as a data row.