Quantitative Reasoning
Quantitative Reasoning
Quantitative Reasoning on the GMAT Focus Edition is 21 Problem Solving questions in 45 minutes - about two minutes each. It is the exam's only math section, because Data Sufficiency now sits inside Data Insights. Every item is a five-choice Problem Solving question with exactly one correct answer, and no calculator is provided. The section rewards structure, estimation, and back-solving from the answer choices far more than long arithmetic.
Core content and rules
- Arithmetic: number properties (divisibility, primes, GCF/LCM, remainders, odd/even), fractions, decimals, percents, ratios, exponents and roots.
- Algebra: linear and quadratic equations, inequalities, functions, sequences, systems of equations.
- Geometry: fundamentals still appear - angles, triangles (including 30-60-90 and 45-45-90), circles, coordinate plane, area and volume - but less heavily than on the classic exam.
- Word problems: rates, combined work, mixtures, overlapping sets, weighted averages, probability and counting.
- Sets: |A ∪ B| = |A| + |B| − |A ∩ B|. For three sets, subtract each pairwise overlap and add the triple overlap back once.
- Combined work: add rates, never times. If A finishes in a hours and B in b hours, together they need ab/(a+b) hours.
- Average speed: total distance ÷ total time. Never average the two speeds unless the times are equal.
Worked example
One pump fills a tank in 4 hours; a second fills it in 6 hours. Working together, how long to fill 5/6 of the tank?
Rates add: 1/4 + 1/6 = 3/12 + 2/12 = 5/12 tank per hour. A full tank therefore takes 12/5 = 2.4 hours, and 5/6 of it takes (5/6)(12/5) = 2 hours.
Notice the trap built in: the arithmetic mean of 4 and 6 is 5, but the true combined time must be less than either individual time. Adding a worker can only speed a job up.
Traps that cost marks
- Solving for x when the question asks for 2x + 3, or reporting a percent when it asks for an amount.
- Averaging speeds over equal distances rather than equal times.
- Treating geometry figures as drawn to scale - they are explicitly not.
- Unit mismatches: minutes versus hours, cents versus dollars, per day versus per week.
- Double-counting members in overlapping-set problems.
- Confusing percent change with percent of: a 20% increase then a 20% decrease leaves 96%, not 100%.