Quantitative and Data Interpretation
Set up the units, then the numbers
Quantitative items rarely demand advanced math; they demand disciplined setup. Expect percentages and percentage change, ratios and rates, weighted averages, unit conversion, proportional reasoning, and straightforward table or chart reading.
Key concepts: distinguish "percent of" from "percentage points"; identify the base of a change, (new − old) ÷ old; never average averages without weighting by group size; use dimensional analysis so units cancel; estimate before computing so a misplaced decimal is obvious; read axis labels, units, and starting values - an axis beginning at 80 exaggerates small changes.
Traps: switching the base mid-problem (a 20% rise then a 20% fall does not return to the start); averaging two group averages equally when group sizes differ; mixing hours and minutes; rounding early and drifting; answer choices built to catch each common slip.
Rule of thumb: write the formula with units before substituting numbers, then sanity-check against a rough estimate. If an answer needs three minutes of arithmetic, look for a simpler relationship.
Worked example: Three analysts process 60 files in 4 hours. At the same rate, how many files do 5 analysts process in 6 hours? Rate per analyst-hour = 60 ÷ (3 × 4) = 5 files. Then 5 analysts × 6 hours × 5 files = 150 files.