Introduction
GMAT test writers use data sufficiency questions
to test your ability to "reason quantitatively."
This stands in sharp contrast to the problem solving
section, which is designed to test how well you manipulate
numbers. If you find yourself doing a lot of
number crunching on the data sufficiency questions,
you are doing something wrong.
Math Concepts
You Should Know
The data sufficiency questions cover math that nearly
any collegebound high school student
will know. In addition to basic arithmetic, you can
expect questions testing your knowledge of
averages, fractions, decimals, algebra, factoring,
and basic principles of geometry such as triangles, circles, and
how to determine the areas and volumes of simple geometric shapes.
The Answer Choices
GMAT data sufficiency questions will all have
the exact same answer choices. Memorize these answer
choices before you take the exam. It will help you
better utilize your time in the quantitative section.
The answer choices are summarized below as you will
see them on the GMAT exam.
 Statement 1 alone is sufficient but statement 2
alone is not sufficient to answer the question asked.
 Statement 2 alone is sufficient but statement 1
alone is not sufficient to answer the question asked.
 Both statements 1 and 2 together are sufficient
to answer the question but neither statement is sufficient
alone.
 Each statement alone is sufficient to answer the
question.
 Statements 1 and 2 are not sufficient to answer
the question asked and additional data is needed
to answer the statements.
Use Process
of Elimination
If statement 1 is insufficient, then choices A and
D can immediately be eliminated.
Similarly, if statement 2 is insufficient, then choices
B and D can immediately be eliminated.
If either statement 1 or 2 is sufficient on its own,
then choices C and E can be eliminated.
A Simple 4
Step Process for Answering These Questions
Many test takers make the mistake of not arming
themselves with a systematic method for analyzing the
answer choices for these questions. Overlooking even one
step in the process outlined below can make a big
difference in the final quantitative score you will
be reporting to your selected business schools.
1.) Study the questions carefully. The
questions generally ask for one of 3 things: 1) a specific
value, 2) a range of numbers, or 3) a true/false value.
Make sure you know what the question is asking.
2.) Determine what information is needed to solve
the problem. This will, obviously, vary depending
on what type of question is being asked. For
example, to determine the area of a circle, you need to know the
circle's diameter, radius, or circumference. Whether or not
statements 1 and/or 2 provide that information will
determine which answer you choose for a data sufficiency
question about the area of a circle.
3.) Look at each of the two statements independently
of the other. Follow the process of elimination
rules covered above to consider each statement
individually.
4.) If step 3 did not produce an answer, then combine
the two statements. If the two statements
combined can answer the question, then the answer
choice is C. Otherwise, E.
Data Sufficiency
Tips and Strategies
Use only the information given in the questions. The
GMAT CAT seeks to measure your ability to distinguish
facts from careless assumptions. Do not rely
on a visual assessment of a diagram accompanying a geometry question to determine
angle sizes, parallel lines, etc. In addition, do not carry
any information over from one question to the next.
Each question in the data sufficiency section of the GMAT stands on its
own. You can count on seeing at least a few questions where
a wrong answer choice tries to capitalize on
this common fallacy.
Do not get bogged down with complicated or lengthy
calculations. As we stated before, these
questions are designed to test your ability to think
conceptually, not to solve math problems.
Use process of elimination. This
GMAT section lends itself perfectly to using the
process of elimination. If time becomes an issue, you
can always look at the 2 statements in either order.
Remember, the order you analyze the two statements in doesn't matter,
so long as you begin by looking at them individually. If
you find statement 1 confusing, you can save time by
skipping to statement 2 and seeing whether it can help
you eliminate incorrect answer choices.
Be on the lookout for statements that tell you
the same thing in different words. When
the 2 statements convey the same exact information,
you will know, through process of elimination, that
the correct answer choice is either D or E. A favorite
ploy of GMAT testers
is to mix ratios and percentages. Here is an example
where Statement 2 simply states backwards the exact
same information provided by Statement 1.
 x is 50% of y
 the ratio of y:x is
2:1
Make realworld assumptions where necessary.
You must assume that, in certain
abstract questions such as "What is the value
of x?", that x might be a fraction
and/or a negative number.
Practice, practice, practice.
The more time you spend practicing data sufficiency questions, the
better able you will be to internalize the tips and
strategies given above. You
will also become very comfortable with the type of questions
from this portion of the test, and will quickly realize
if there are any math areas, such as geometry or algebra
where you need to brush up your skills. When
it comes time to sit for the GMAT,
you will want to know key math formulas and data
relationships off the top of your head.
Click
here to see our data sufficiency practice questions.
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