This tip for improving your GMAT score was provided by David Newland at Veritas Prep.
Remember this: You lean toward A B D; but you jump to C vs. E.
In the first part of this article, we learned that some question types are ones where you can generally do more with less: In such cases, you should approach the question by “leaning” a little toward A B D, since those are the answers in which one statement alone is sufficient. Question types where you lean A B D include Geometry, Work/Rate, Ratio, Percentage, and Yes/No questions in general. The “lean” is a slight one; remember that a Geometry question can always turn out to be answer choice C or E.
Jumping to C vs E:
On the other hand, on many individual questions, the statements themselves cause you to quickly “jump” to C vs. E. This happens when the statements are each clearly insufficient, ruling out A, B, and D right from the start. In this case, the answer can only be C or E.
Jumping to C vs. E is a definitive move triggered by a pair of clearly not-sufficient answer choices. The following problem from the Veritas Data Sufficiency book is a good example:
Is y a positive number?
(1) 2x +y > 27
(2) X – 3y
As you can see, there are two inequalities, one in each statement, and each inequality has two variables. Neither of these statements is sufficient alone—not even close. These statements would not be sufficient, even if they were equations. Even if we knew that “2x + y = 27” it would still be possible to select any number of values for x and y. And with an inequality, we know even less about x and y.
It is important that you learn to recognize questions featuring two statements that are clearly not sufficient. Unlike “lean ABD,” there are no specific categories that cause you to jump to C vs. E; the statements themselves are clearly not sufficient.
Here is a further example, this time from geometry:
(You are given a diagram of a circle with a chord AB that is clearly not the diameter and a center point C).
In the figure above, what is the area of the circle with center C?
(1) The length of minor arc AB is one-sixth of the circumference.
(2) The length of chord AB is 8.
This is a classic example of “jump to C vs. E.” Statement 1 is not sufficient because in order to calculate the area of the circle, you must have at least one length. With statement 1 alone, you have no idea of the scale of this circle. It could be the size of a dinner plate or it could be the size of a planet.
Statement 2 is also clearly not sufficient alone. Statement 2 provides the needed length, but it is not in context. What does chord AB represent? Since it is clearly not the diameter, there is no way to use the length of 8 in order to find the area.
At the very least, you will need the information from both statements together; even that may not be enough. So jump to C vs. E and let the real work begin as you attempt to find the area. using the information from both statements.
Jumping to C vs. E can help you when you do not completely understand a problem. If you know that neither statement alone is sufficient, you have narrowed the choices down to a 50-50 proposition. This can be important as you face difficult questions during the exam. But jumping to C vs. E gives you a further advantage. It allows you to work more efficiently as you focus your attention on the real question at hand: “Are both statements together sufficient?” C vs. E problems are often labor-intensive, so a quick jump can save you the time you need to roll up your sleeves and get to work.
As you practice data sufficiency, look for opportunities to lean toward A B D and jump to C vs. E.
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