Today’s GMAT Tip comes to us from Kaplan. In this article, Kaplan guest author Eli Meyer provides helpful advice on how to save time by recognizing patterns on the Data Sufficiency section of the GMAT:

In our GMAT prep courses, we recommend that students begin to solve GMAT Data Sufficiency problems at the question stem. The stem often provides vital information, and without understanding the question itself, it’s impossible to accurately evaluate the statements. However, sometimes question stems can be complex and impenetrable, especially if you’re behind schedule and the clock is ticking. In those cases, the statements can help you make an educated guess about possible answers. There are three patterns of Data Sufficiency statements that can narrow down the information, each of which involves overlapping information between statements, or between a statement and what you already know from the stem or common sense. Recognizing these patterns can be a useful time saver on test day.

Pattern I: Identical statements

1) 2x + 3y = 6

2) 6y = 12 – 4x

The GMAT will never literally repeat a statement, but it might give two statements that provide identical information. For example, “50% chance of heads” and “50% chance of tails” are, on a fair coin, exactly equivalent mathematically. Or, as above, if you add 4x to both sides of statement 2:

6y + 4x = 12

and you then divide both sides by two:

3y + 2x = 6

you will find that the two statements provide the same information.

When the statements are identical, it’s impossible for one statement to be sufficient without the other also being sufficient; similarly, combining them can’t ever help because we are just taking the same info twice! Regardless of the question stem, the answer must be (D) or (E) in this specific scenario.

Pattern II: One statement implies the other

1) x is positive

2) x is prime

Sometimes, one statement provides enough information by itself to make the other redundant. For example, in the case above, prime numbers are (by definition) positive. Normally, we recommend that students evaluate the statements one at a time, but in this case one statement includes all the information of the other statement. Other examples: “1) x > 4” implies that “2) x > 2”, and “1) y is even” must be true whenever “2) y / 2 is even” is true. When we recognize this pattern, we can eliminate two answer choices. In our first example, if knowing x is positive is enough to answer the question, then knowing x is prime tells us x is positive and so is also sufficient. 1) can never be the only sufficient statement, and (A) can never be the answer, regardless of the question stem. On the other hand, if knowing x is prime is insufficient, then telling as that x is also positive adds literally no information. Statements 1) and 2) combined are exactly equivalent to statement 2) alone. If 2) alone . . . → Continue Reading

Today’s GMAT Tip comes from our friends at Knewton.  In this article, they provide helpful information about how to answer Data Sufficiency questions on the GMAT.  Read on to see what they have to say!

Here’s another quick tip for those of you still struggling with the pitfalls of Data Sufficiency.

Let’s take a look at the following Official Guide DS problem:

If p and q are positive integers and pq = 24, what is the value of p?

(1)  q/6 is an integer

(2)  p/2 is an integer

It just so happens that this is a value-based question:  When we’re asked “what is the value of p?”, we’re being asked to provide a single value for p.  If a statement or combination of statements cannot give us a single value, then it must be insufficient.

. . . → Continue Reading

Today’s GMAT Tip comes from our friends at Knewton.  In this article, they provide helpful advice on how to accurately compare fractions when taking the GMAT.  Read on to see what they have to say!

When discussing fractions, I often find a very interesting area of confusion among students. I’ll ask them to compare, for example, 1/3 and 1/4. Almost everyone correctly answers that 1/4 is smaller. “How do you know?” I’ll ask. And this is where the confusion starts. More often then not, most of the class will say something like, “When the denominator is larger, the fraction is smaller.”

But is that always true?

Well, in this case, sure, it’s true. But what if I asked to compare, for example, -1/3 and -1/4? Now, it would be incorrect to say the number with the larger denominator is smaller. Now that we’re on the negative side of the number line, everything is reversed. -1/4 is actually larger than -1/3.

The confusion is only compounded when we get to fractions involving exponents. Let’s say b is a proper fraction (i.e. a number between 0 and 1). It’s easy enough to see that, for example, b^5 will be less than b^3. For example, (1/2)^5 = 1/32 is less than (1/2)^3 = 1/8. . . . → Continue Reading

Today’s GMAT Tip comes to us from Kaplan. In this article, Kaplan GMAT instructor Bret Ruber explains how to avoid common exponent mistakes when taking the GMAT:

Exponent questions are among those that give GMAT-preppers the most difficulty.  The key to answering exponent questions correctly is to remember all of the rules you must follow.  For example, knowing that ab x ac = ab+c, and ab x cb = (ac)b will be essential to answering exponent questions correctly.

However, you also want to avoid common exponent mistakes.  This is especially important because wrong answer choices in exponent questions, as with the rest of the GMAT, will be based on common test-taker errors.

Today’s GMAT Tip comes from our friends at Knewton.  In this article, they explain how to use the concept of “weighted averages” to help answer quantitative questions more quickly on the GMAT.  Read on to see what they have to say!

In last week’s post, I discussed how weighted averages are often tested conceptually and thus show up on Data Sufficiency problems. However, even when weighted average problems appear on the more results-oriented Problem Solving questions, this conceptual understanding can be mighty handy. As I said in a previous post, the GMAT is not a speed calculation test, but that doesn’t mean the test won’t reward you if you can find conceptual shortcuts!

If you think I have another official GMAT problem handy, you are right . Feel free to give it a shot before reading my explanation.

Last year Manfred received 26 paychecks. Each of his first 6 paychecks was $750; each of his remaining paychecks was $30 more than each of his first 6 paychecks. To the nearest dollar, what was the average (arithmetic mean) amount of his paychecks for the year?

(A) $752 (B) $755 (C) $765 (D) $773 (E) $775 . . . → Continue Reading

Today’s GMAT tip comes from test prep firm ManhattanGMAT. In this article, they provide helpful tips for how to answer divisibility problems on the quantitative section of the GMAT.  Read on to see what they have to say!

We’ve got another GMATPrep word problem on tap for today, but this one’s in the area of divisibility (number properties). These kinds of problems often include a lot of math vocab; we need to make sure both that we understand the precise words used and concepts being described and that we don’t forget or overlook any of the pieces.

Set your timer for 2 minutes…. and… GO!

* ” If m is a positive odd integer between 2 and 30, then m is divisible by how many different positive prime numbers?

“(1) m is not divisible by 3.

“(2) m is not divisible by 5.”

. . . → Continue Reading

Today’s GMAT Tip comes to us from Kaplan. In this article, Kaplan GMAT instructor Bret Ruber provides tips for answering questions involving multiplication on the GMAT:

When working on the GMAT quantitative section, it is always important to remember that the questions are written so that they can be completed within about a two-minute timeframe.  If you encounter a problem and the math seems as if it will take more than two minutes to do, it generally means that either you made an error or a faster way to solve exists.  One of the most frequent cases in which the latter occurs is on problems that involve multiplication, since there are no calculators on the GMAT.

Unlike long division, which can be very useful on the GMAT, longhand multiplication is almost never necessary.  Instead you should always look for shortcuts to solve.  Not only will this be quicker, but it will also provide fewer opportunities for careless errors.