The other questiontype is the famous, dreaded, Data Sufficiency.
Here, you must determine whether you have enough information to
answer the question. Sometimes, but not always, the question
itself provides useful but incomplete information. Once you've
digested this, you then consider two additional propositions and
decide if one, both or neither of them provides the additional
information you need. The answer choices are standardized based
on the combination of propositions needed to correctly answer
the question. Data Sufficiency is very tricky for the
uninitiated, but because up to 15 question in the section are
this type, your performance on Data Sufficiency will make or
break your Quantitative score. Let's see how Data Sufficiency
works with the following sample question:
Two automobile manufacturers, Nash and Tucker,
declared profits on the sales of their cars for the year 1998.
Which manufacturer posted the greatest profit?
1. Nash's total cost per automobile is 78% of
the sales price, and in 1998, it sold 250,000 automobiles.
2. Tucker's total cost per automobile is 85%
of the sales price, and in 1998, it sold 200,000 automobiles.
A. Statement 1 BY ITSELF is sufficient to
answer the question, but statement 2 by itself is not.
B. Statement 2 BY ITSELF is sufficient to
answer the question, but statement 1 by self is not.
C. Statement 1 and 2 TAKEN TOGETHER are
sufficient to answer the question, but NEITHER statement BY
ITSELF is sufficient.
D. Either statement BY ITSELF is sufficient to
answer the question.
E. Statements 1 and 2 TAKEN TOGETHER are NOT
sufficient to answer the question. More data pertaining to the
problem is necessary.
Tips: Data Sufficiency rewards a methodical approach.
Start with the question itself: what do we want to know?
Answer: which manufacturer posted the greatest profit.
So we need information about both Nash's and Tucker's
profits, right? Now look at Statement 1 BY ITSELF. Nash's total
cost per automobile is 78% of the sales price, and in 1998, it
sold 250,000 automobiles.
Does this tell you anything about Tucker's profit? No. So
Statement 1 BY ITSELF is not sufficient. What answer choices can
you eliminate? The first and the fourth.
Now let's repeat the process looking at Statement 2 BY SELF.
Tucker's total cost per automobile is 85% of the sales price,
and in 1998, it sold 200,000 automobiles.
There is no information here about Nash. So Statement 2 BY
ITSELF is not sufficient. We can now cancel the second choice.
What's left? We have to look at Statements 1 and 2 TAKEN
TOGETHER.
Nash's total cost per automobile is 78% of the sales price,
and in 1998, it sold 250,000 automobiles AND Tucker's total cost
per automobile is 85% of the sales price, and in 1998, it sold
200,000 automobiles.
Reading. The statements give us a relationship between cost
and sales price for each company, but can we calculate actual
figures for profit? No, because we don't have any real numbers
to work with. Can we compare these relationships directly? Only
if the sales prices are the same, and this we don't know!
Statements 1 and 2 TAKEN TOGETHER are therefore not sufficient.
Cancel out the third answer choice.
By elimination, we know the last answer choice must be the
correct response. By now, you might be thinking that Data
Sufficiency is a long, slow, painful process. But like any
method, the more you practice, the faster you get.
