Quantitative Aptitude: Arithmetic Speed and Data Interpretation
Quantitative Aptitude in LIC AAO tests speed with arithmetic and data interpretation rather than advanced mathematics. Expect percentage, ratio, time-work, speed-distance, SI/CI, mixtures, number series, approximation, quadratic equations, probability and DI.
Core rules
- Memorise fraction-percentage equivalents: 1/8 = 12.5%, 1/6 = 16.66%, 1/16 = 6.25%; use them to replace long division.
- In successive percentage change, use net = a + b + ab/100; a 20% rise then a 20% fall gives -4%, not 0%.
- Time-work: take total work as the LCM of days; efficiency is work per day.
- SI = PRT/100; CI = P(1+R/100)^T - P; for two years, CI - SI = P(R/100)^2.
- In DI, read units and the base year first; calculate only the values the options require.
Worked example
A completes a job in 12 days and B in 18 days. Together: LCM 36 units; A does 3 units/day, B 2 units/day; combined 5 units/day; time = 36/5 = 7.2 days, i.e. 7 days 4.8 hours.
Traps
- Applying a second discount on the original price instead of the reduced price.
- Using the SI formula for CI or forgetting to subtract P.
- In ratio, changing the base after an increase.
- Rounding too early in approximation questions.
- Ignoring "approximately" and choosing the exact-looking distractor.