How to Approach Quantitative Comparison Problems on the GRE
About one-third of the GRE math questions are Quantitative Comparisons (QC), with plenty of traps to trip you. QCs demand thought and insight to recognize and sidestep common traps; otherwise, you may stumble into some unnecessary, heavy-duty math.
A QC question shows two quantities, intuitively labeled Quantity A and Quantity B. The quantities can be numbers, variables, equations, words, figures, and so on. Your job is to compare the quantities and determine whether one is greater than the other, they’re equal, or the relationship can’t be determined from the information provided.
Due to their number, the QC questions consume a good chunk of your time. To conserve time, memorize the QC answer choices prior to test day. Whatever the information, the answer choices for QCs are always the same:
(A) Quantity A is greater.
(B) Quantity B is greater.
(C) The two quantities are equal.
(D) The relationship cannot be determined from the information given.
As long as you know the choices, you don’t need to read and think about them each time.
Consider paraphrasing the answer choices to make them easier to memorize and save even more time:
(A) A is greater.
(B) B is greater.
(C) They’re equal.
(D) You need more information.
The challenge in answering QC questions correctly is knowing where to begin. You can save considerable time and frustration by following this simple, three-step approach:
Simplify Quantity A.
Simplify may mean solving an equation, talking through a word problem, or simply taking an estimate of what’s there. Sometimes a ballpark estimate is sufficient.
Simplify Quantity B.
Again, simplify can mean solving an equation, talking through a word problem, or estimating the quantity.
Compare the two quantities.