Quantitative Aptitude and Numerical Ability: Arithmetic and Mensuration
What the quantitative paper tests
KPTCL quantitative questions cover percentages, ratio and proportion, averages, profit and loss, simple and compound interest, time-work, speed-distance, and mensuration. The fastest route is usually to convert the problem into one base quantity or one equation.
Core rules
- Percentage change=(new−old)/old×100; successive changes multiply, not add.
- Simple interest SI=PRT/100; compound amount A=P(1+R/100)^T.
- Work: if A finishes in x days and B in y days, together they finish in xy/(x+y) days.
- Speed= distance/time; for equal distances, average speed=2v₁v₂/(v₁+v₂).
- Mensuration: circle area=πr²; cylinder volume=πr²h; rectangle area=l×b.
Worked example
A can finish a job in 12 days and B in 18 days. One day’s work=1/12+1/18=3/36+2/36=5/36. Time together=36/5=7.2 days. The result is less than either individual time because they work simultaneously; adding 12 and 18 would be wrong.
Traps
Applying percentage increase and decrease as if they cancel; using SI formula for CI; forgetting to convert minutes to hours in speed problems; and using diameter instead of radius in circle or cylinder formulas.