Mathematics and Quantitative Aptitude: Arithmetic, Mensuration and Data
Quantitative Aptitude in the BPSC screening test is arithmetic-heavy and time-bound. The recurring topics are number system, HCF and LCM, percentage, ratio and proportion, average, profit and loss, simple and compound interest, time and work, pipes and cisterns, speed and distance, mensuration, and simple data interpretation from tables or bar charts.
Core rules to hold ready
- Percentage change is always measured on the base that the question names, not on the changed value.
- Two successive changes of x% and y% equal a single change of x + y + xy/100 (use minus for discounts).
- Simple interest = PRT/100; compound interest = P(1 + r/100)^t − P.
- If A alone takes a days and B alone b days, together they take ab/(a + b) days.
- 1 m/s = 3.6 km/h, and average speed for equal distances is the harmonic mean, 2xy/(x + y).
Worked example
A trader marks an article 40% above cost and allows a 25% discount. What is the profit? Take cost price = 100. Marked price = 140. Selling price = 140 × 0.75 = 105. Profit = 105 − 100 = 5, so the answer is 5%.
Traps that cost marks
Successive discounts of 10% and 20% give 28%, not 30%. Simple and compound interest are equal only for the first year. Ratios must be converted to the same unit before use. Approximation should be applied only after checking the option gaps, because BPSC options are often close enough to defeat loose rounding.
Practice by timing sets of ten questions, since accuracy under a two-hour, negative-marked paper matters as much as method.