Quantitative Reasoning
What the section tests
Quantitative Reasoning measures numerical problem-solving in short, practical contexts. Topics include percentages and percentage change, ratios and proportions, rates and unit conversions, averages (including weighted means), currency, simple geometry, and interpretation of tables, charts and scales. A basic on-screen calculator is available, but estimation is often faster.
Concepts to master
Convert all quantities to consistent units before calculating. Distinguish percentage points from percentage change: a rise from 20% to 25% is 5 percentage points but a 25% relative increase. For reverse percentages, divide by the multiplier rather than subtracting the stated percentage. For rates, use amount = rate × time and rearrange carefully. For weighted averages, weight each group by its size.
Traps
The commonest errors are unit slips (minutes versus hours, grams versus milligrams), misreading a graph's scale or starting value, using the wrong denominator, and rounding too early. Also watch for questions asking 'how many more' rather than 'how many', and for options that differ only by a factor of 10 or 100.
Worked example
A drug is prescribed at 15 mg/kg/day, divided into three doses. A 60 kg patient needs 15 × 60 = 900 mg/day, so 300 mg per dose. With stock at 50 mg/mL, each dose is 300 ÷ 50 = 6 mL. Rule of thumb: write down the units at each step; if the units do not cancel to the required unit, the calculation is wrong.