
Guessing and the Math IIC
Should you guess on the SAT II Math IIC? We’ll begin to
answer this question by posing a question of our own:

The answer, of course, is ^{1}
/_{5} . But just as important,
you should recognize that the question precisely describes the situation
you’re in when you blindly guess the answer to any SAT II Math IIC
question: you have a ^{1}/
_{5} chance of getting the question
right. If you were to guess on ten questions, you would, according
to probability, get two questions right and eight questions wrong.
 2 right answers gets you 2 raw points
 8 wrong answers gets you 8 –
^{1}/_{4} point = –2 raw points
Those ten answers, therefore, net you a total of 0 points.
Your guessing was a complete waste of time, which is precisely what
the ETS wants. They designed the scoring system so that blind guessing
is pointless.
Educated Guessing
But what if your guessing isn’t blind? Consider the following
question:

Let’s say you had no idea how to solve this problem, but
you did realize that 0 multiplied by any number equals 0 and that
0 + 2 0 cannot add up to 6. This means
that you can eliminate “0” as a possible answer, and now have four
choices from which to choose. Is it now worth it to guess? Probability
states that if you are guessing between four choices, you will get
one question right for every three you get wrong. For that one correct
answer you’ll get 1 point, and for the three incorrect answers you’ll
lose a total of ^{3}/
_{4} of a point. 1 –
^{3}/_{4} =
^{1}/_{4} ,
meaning that if you can eliminate even one answer, the odds of guessing
turn in your favor: you become more likely to gain points than to
lose points.
Therefore, the rule for guessing on the Math IIC is simple: if
you can eliminate even one answerchoice on a question, you should
definitely guess. And if you follow the critical thinking
methods we described above about how to eliminate answer choices,
you should be able to eliminate at least one answer from almost
every question.
Guessing as Partial Credit
Some students feel that guessing is similar to cheating,
that in guessing correctly credit is given where none is due. But
instead of looking at guessing as an attempt to gain undeserved
points, you should look at it as a form of partial credit. Take
the example of the question above. Most people taking the test will
see that adding two zeros will never equal six and will only be
able to throw out that choice as a possible answer. But let’s say
that you also knew that negative numbers added together cannot equal
a positive number, 6. Don’t you deserve something for that extra
knowledge? Well, you do get something: when you look at this question,
you can throw out both “0” and “–2” as answer choices, leaving you with
a ^{1}/_{3} chance
of getting the question right if you guess. Your extra knowledge
gives you better odds of getting this question right, exactly as
extra knowledge should.
