Quantitative and Analytical Skills
This section covers arithmetic, algebra, geometry, ratios, percentages, averages, and data interpretation, plus analytical reasoning over tables and graphs. The math is rarely advanced; the challenge is speed, accuracy, and translating word problems into equations.
Core concepts
Master percentage change (increase = change/original × 100), ratio and proportion, averages and weighted averages, work-rate problems, and basic geometry formulas (area, circumference, Pythagorean theorem). For data interpretation, read axis labels and units before computing; many errors come from misreading scale.
Common traps
Percentage traps: a 20% increase followed by a 20% decrease does not return to the original value. Rate traps: average speed is total distance over total time, not the average of speeds. Unit traps: minutes versus hours, or centimeters versus meters. In data questions, a distractor often uses the wrong year or column.
Worked example
A shirt costs 800 afghanis after a 20% discount. What was the original price? Let original = x. Then 0.8x = 800, so x = 1000. A common wrong answer is 960, obtained by adding 20% to 800; discount and markup apply to different bases. Rule of thumb: identify the base of every percentage before calculating.
Strategy
Estimate before computing to eliminate absurd options. Substitute answer choices back into equations when solving forward is slow. Keep units consistent throughout.