GRE: Introduction to Quantitative Comparisons

Quantitative Comparison questions require you to make a comparison between quantities in two columns. You are to decide if one column is greater, if the columns are equal, or if no comparison can be determined from the information given.

Ability Tested

Quantitative Comparison tests your ability to use mathematical insight, approximation, simple calculation, or common sense to quickly compare two given quantities.

Basic Skills Necessary

This question type requires 12th-grade competence in school arithmetic, algebra, and intuitive geometry. Skills in approximating, comparing, and evaluating are also necessary. No advanced mathematics is necessary.

Directions

You are given two quantities, one in column A and one in column B. You are to compare the two quantities and choose

  1. if the quantity in Column A is greater;

  2. if the quantity in Column B is greater;

  3. if the two quantities are equal;

  4. if the comparison cannot be determined from the information given.

Common Information: Information centered above columns refers to one or both columns. A symbol that appears in both columns represents the same thing in each column.

Analysis

  • The purpose here is to make a comparison; therefore, exact answers are not always necessary. (Remember that you can tell whether you are taller than someone in many cases without knowing that person's height. Comparisons such as this can be made with only limited or partial information — just enough to compare.)

  • Choice D — the comparison cannot be determined from the information given-is not a possible answer if there are values in each column, because you can always compare values.

  • If you get different relationships, depending on the values you choose for variables, then the answer is always D. Notice that there are only four possible choices here.

  • Note that you can add, subtract, multiply, and divide both columns by the same value, and the relationship between the columns will not change. Exception: You should not multiply or divide each column by negative numbers, because the relationship reverses. Squaring both columns is permissible, as long as each side is positive.