GMAT Problem Solving
Introduction
The problem solving questions of the GMAT test
are designed more to test your understanding of the underlying
mathematical concepts than to test your ability to actually
carry out the quantitative procedures accurately.
Fortunately for many test takers, advanced quantitative
areas such as trigonometry and calculus are not
tested on the GMAT. To score well, you will only need to be
knowledgeable of the basic arithmetic, geometry, and algebra
that are taught at the high school level. Any decent GMAT prep
book will cover these quantitative concepts.
Problem Solving Tips and Strategies
Read the questions carefully. This
is the most common pitfall that GMAT test takers make and it
is hard for us to overstate this. There is a big difference
between the questions "Which of the following may be true?"
and "Which of the following may not be true?" The
test writers deliberately include choices that correlate to
common misinterpretations of their questions.
Use your scrap paper for every question.
No matter how easy the question appears, you should utilize
your scrap paper. Seeing the calculation on paper will help
you avoid many of the easy mistakes and the corresponding answer
choice designed to exploit that mistake. Also, once you record
your answer on the GMAT CAT, you can't go back and change it.
This aspect of the CAT makes this tip even more effective.
Do not get bogged down with complicated or
lengthy calculations. We have looked at hundreds of
these GMAT questions and they are deliberately designed to make
such calculations unnecessary. You are overlooking a shortcut
if you find yourself getting bogged down in this way.
The "guesstimating" technique is
extremely effective on this exam. Most of the time
the answer is a value, the choices will not be very close to
each other. As a result, if you can save time and closely guesstimate
the answer to be 30% and the choices are 4%, 13%, 29%, 47%,
and 81%, then you will know the answer must be 29%. Congratulations,
you just saved a lot of time on this question and avoided a
longer calculation that would have greatly increased the chances
of committing a math error!
Learn how to work backwards. If you
are completely stuck on a question, you can always try to plug
in an answer and work backwards. If you do this, we suggest
you start by plugging in the middle value. If this answer does
not correctly answer the question, it may at least tell you
if you need to plug in a smaller or larger value. In this case,
you have narrowed your initial 5 choices down to 2.
Convert quantities freely. There
are often shortcuts available to you if you see certain relationships
between the numbers used in the problems. Keep in mind, the
GMAT test writers never haphazardly select numbers
for their questions. This technique is most often used in questions
where you get the urge to pull out a calculator. One easy conversion
to remember is that, at least for purposes of the GMAT, π
= 22/7.
Use process of elimination as a last resort.
The GMAT writers have historically arranged the answer choices
in ascending numerical value. Even if you are unable to hone
in on the correct answer, chances are guesstimating, working
backwards, or some other technique will help you at least eliminate
many of the wrong choices.
Practice, practice, practice. If
you spend some time practicing these questions, you will be
able to internalize these tips and strategies. You will also
become very comfortable with the questions from this portion
of the test and will quickly realize if there are any math areas
such as geometry or algebra where you will need to brush up
on your skills. When it comes time to sit for the GMAT, you
will want to know the total number of degrees in the sides of
a triangle, the calculation for the area of a circle, etc off
the top of your head.
Problem-Specific Tips and Techniques
There are a few distinct types of problems that
have their own specific tips and strategies:
Geometry Problems
Assume the diagrams are drawn accurately unless
the question specifically states otherwise. Do not,
however, rely on your visual judgment to answer these questions.
The test writers never allow their questions to
be that easily answered. One common mistake is to assume that
2 lines form a right angle when this is not specifically indicated.
Do not make this assumption as it is one of the most common
mistakes made on the GMAT.
Spend at least 30 seconds reviewing the diagrams.
Many implicit facts and numbers are often contained inside these
figures. Due to the computer-adaptive nature of today's GMAT,
you will need to sketch out the diagrams on your scrap paper
to deduce the implicit facts from the data explicitly given.
Graph Problems
Spend at least 30 seconds reviewing the graphs
and tables. Graph problems are not designed to include
hard math calculations. Instead they are designed to test your
ability to interpret and use information contained in the graphs
and tables. As a result, you will be well suited to study the
structures and basic contents of the graphs and tables. The
axis labels, legend key, and units of measurement are more
important than the actual data presented.
Make sure you are familiar with bar, circle,
and line graphs. These are the 3 graph types most
commonly presented on the GMAT.
You can rely on visual estimations for the
bar graphs and line charts. The test writers will
not use visual tricks for deception. You often times will have
to trust the visual estimation to determine the correct answer.
Note: this will not work for geometry questions however.
"Weird" Problems
Identification is half the battle.
AdmissionsConsultantsSM defines "weird"
as problems that simply test your reasoning skills and not your
quantitative skills. These questions are widely considered the
most intimidating on the entire exam.
An excellent example of this genre of questions
is when a new function is presented that you never learned in
school. When you come across this type of problem, you will
greatly improve your odds of answering it correctly by calmly
and methodically imitating the "logic" presented in
the question. If this fails, you can always work backwards.
Word Problems
Build equations for word problems.
When dealing with a word question (such as trains traveling
at a certain speed) build an equation that will help you get
the answer. Use obvious letter symbols such a "A"
for train A, "B" for Bob's age, etc.
Don't waste time looking for subtle meanings.
You can make reasonable assumptions with these questions. The
test writers are not trying to trick you in this way.
Problem solving practice
Questions
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