Quantitative Aptitude
Quantitative Aptitude in CEPTAM Tech-A checks speed and accuracy across arithmetic and elementary mensuration. Questions are short but time-pressed, so formula recall matters more than long derivation.
High-yield areas
- Number system: divisibility, HCF/LCM, remainders, unit digit.
- Percentage, ratio and proportion, average, mixtures and alligation.
- Profit and loss, discount, simple and compound interest.
- Time and work, pipes and cisterns, speed-distance-time, trains and boats.
- Mensuration of 2D/3D figures and data interpretation from tables and bar charts.
Worked example
A completes a job in 12 days and B in 18. Working together, one day's work = 1/12 + 1/18 = 3/36 + 2/36 = 5/36, so time = 36/5 = 7.2 days, i.e. 7 days 4 hours 48 minutes. If both are paid Rs. 3,600, A's share follows work done: A completes (1/12) x 7.2 = 0.6 of the job, so Rs. 2,160.
Traps
Check the unit asked (days vs hours, cm vs m). For successive discounts multiply factors (0.9 x 0.95); never add them. Average speed is total distance divided by total time, not the mean of the two speeds. Compound interest exceeds simple interest from the second year onward, so never use the SI formula for multi-year CI. In data interpretation, confirm whether a percentage is of the total or of a subgroup.
Key points
- Convert all quantities to one unit before calculating.
- Use the fraction-of-work method for time and work and pipes.
- Successive percentage change: a + b + ab/100.
- Two articles sold at the same price, one at x% profit and one at x% loss, always give a net loss of (x/10)^2 percent.
- For trains, distance = length of train + length of platform when crossing.