c-trapHave you heard of the C-Trap? I’m not going to tell you what it is yet. Try this problem from GMATPrep® first and see whether you can avoid it

* “In a certain year, the difference between Mary’s and Jim’s annual salaries was twice the difference between Mary’s and Kate’s annual salaries. If Mary’s annual salary was the highest of the 3 people, what was the average (arithmetic mean) annual salary of the 3 people that year?

“(1) Jim’s annual salary was $30,000 that year.

“(2) Kate’s annual salary was $40,000 that year.”

I’m going to do something I normally never do at this point in an article: I’m going to tell you the correct answer. I’m not going to type the letter, though, so that your eye won’t inadvertently catch it while you’re still working on the problem. The correct answer is the second of the five data sufficiency answer choices.

How did you do? Did you pick that one? Or did you pick the trap answer, the third one?

Here’s where the C-Trap gets its name: on some questions, using the two statements together will be sufficient to answer the question. The trap is that using just one statement alone will also get you there—so you can’t pick answer (C), which says that neither statement alone works.

In the trickiest C-Traps, the two statements look almost the same (as they do in this problem), and the first one doesn’t work. You’re predisposed, then, to assume that the second statement, which seemingly supplies the “same” kind of information, also won’t work. Therefore, you don’t vet the second statement thoroughly enough before dismissing it—and you’ve just fallen into the trap.

How can you dig yourself out? First of all, just because two statements look similar, don’t assume that they either both work or both don’t. The test writers are really good at setting traps, so assume nothing.

Second, imagine that you’re teaching your 10-year-old niece how to do algebra. She’s never done this before but she’s pretty bright. She understands your explanation of what variables are and how they work. She knows that, if you give her an equation with 3 variables, and then give her values for 2 of those variables, she’ll be able to solve for the third one. What answer is she going to pick on the above problem?

Hmm. She’d pick (C) also, since that gives her values for two of the three variables in the equation that she can write from the question stem.

It’s obvious, in fact, that using the two statements together will allow you to find all three salaries, in which case you can average them. In the test-prep world, this is what’s known as a Too Good To Be True answer. If your 10-year-old niece, who just learned algebra, could get to the same answer, then chances are you’re falling into a trap. Stop, take a deep breath, and scrutinize those statements individually!

Here’s how to solve the problem.

Step 1: Glance Read Jot

Take a quick glance; what have you got? DS. Story problem: understand the story before writing.

The question asks for the average of the three salaries. What do you actually need to know in order to find an average? Right, the sum. So can you find the sum of the three salaries?

Jot that on your scrap paper: M + J + K = ?

Step 2: Reflect Organize

The first sentence provides an equation, so translate it. (Note that the second sentence says Mary’s salary is the highest.)

The positive difference between Mary’s and Jim’s salaries has to be MJ, since M is larger. Likewise, the positive difference between Mary’s and Kate’s salaries has to be MK, since M is larger.

Here’s the translated formula:

MJ = 2(MK)

Step 3: Work

By itself, that doesn’t look very helpful, but anytime DS gives you a formula that isn’t simplified, simplify it. Multiply out the right-hand side and also get “like” variables together:

MJ = 2(MK)

MJ = 2M – 2K

- J = M – 2K

Notice two things: first, negatives are annoying. Second, this formula (so far) doesn’t look anything like the question: M + J + K = ?

Is there any way to remedy those two things?

Move the –J over: 0 = M – 2K + J.

Notice that 2K is never going to fit the question, which has only K. Move that away from the others: 2K = M + J.

Interesting. The right-hand side now matches part of the question. In fact, you could substitute:

M + J + K = ?

2K = M + J

Therefore, the question becomes 2K + K = ?

If you know what K is—only K!— then you can solve. (Note: we call this process Rephrasing. Use the information given in the question stem to rephrase the question in a more simplified form.)

“(1) Jim’s annual salary was $30,000 that year.”

J = 30,000. If you plug that into M + J + K = ?, it isn’t sufficient. If you plug that into 2K = M + J, you get 2K = M + 30,000, which still isn’t sufficient. Knowing only J doesn’t get you very far. This statement is not sufficient; eliminate answers (A) and (D).

“(2) Kate’s annual salary was $40,000 that year.”

Bingo! If you know Kate’s salary, then you know the sum of all three. This statement is sufficient to answer the question.

The correct answer is (B).

If you don’t rephrase up front, and instead go through all of the work of plugging in the values for statements (1) and (2), then you may still discover the correct answer. You’ll take longer, though. You may also fall into the trap of assuming that statement (2) won’t work because it looks so very similar to statement (1) and that one didn’t work.

Key Takeaways: Data Sufficiency

(1) Don’t just write down the information in the question stem, shrug, and go straight to the statements. Push yourself to try to rephrase the question before you go to the statements.

(2) Use standard math steps and your test-taker savvy to help you know how to simplify. It’s standard algebra to try to get “like” variables together in equations. A negative sticking out in front of an equation is ugly, so that was clue #2. Finally, you’re ultimately trying to match the information in the question (M + J + K = ?), so try to rearrange your rephrased equation to match the question as much as possible. Then see whether you can substitute in to make that question simpler!

(3) Keep an eye out for Too Good to Be True answers. If an answer seems pretty obvious, then there’s a good chance you’re falling into a trap!

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.

 

Navigator-gmatRecently, we talked about how to create Official Guide (OG) problem sets in order to practice for the test. I have one more component to add: track your work and analyze your results to help you prioritize your studies.

In the first half of this article, we talked about making problem sets from the roughly 1,500 problems that can be found in the three main OG books. These problems are generally regarded as the gold standard for GMAT study, but how do you keep track of your progress across so many different problems?

The best tool out there (okay, I’m biased) is our GMAT Navigator program, though you can also build your own tracking tool in Excel, if you prefer. I’ll talk about how to get the most out of Navigator, but I’ll also address what to include if you decide to build your own Excel tracker.

(Note: GMAT Navigator used to be called OG Archer. If you used OG Archer in the past, Navigator brings you all of that same functionality—it just has a new name.)

What is GMAT Navigator?

Navigator contains entries for every one of the problems in the OG13, Quant Supplement, and Verbal Supplement books. In fact, you can even look up problems from OG12. You can time yourself while you answer the question, input your answer, review written and video solutions, get statistics based on your performance, and more.

Everyone can access a free version of Navigator. Students in our courses or guided-self study programs have access to the full version of the program, which includes explanations for hundreds of the problems.

How Does Navigator Work?

First, have your OG books handy. The one thing the program does not contain is the full text of problems. (Copyright rules prevent this, unfortunately.)

When you sign on to Navigator, you’ll be presented with a quick tutorial showing you what’s included in the program and how to use it. Take about 10 minutes to browse through the instructions and get oriented.

When you reach the main page, your first task is to decide whether you want to be in Browse mode or Practice mode.

Practice mode is the default mode; you’ll spend most of your time in this mode. You’ll see an entry for the problem along with various tools (more on this below).

Browse mode will immediately show you the correct answer and the explanation. You might use this mode after finishing a set of questions, when you want to browse through the answers. Don’t reveal the answers and explanations before you’ve tried the problem yourself!

Here’s what you can do in Practice mode:

—Start the timer, work on the problem, then input your answer (at which point the timer will stop). The program will automatically save the time spent for that problem, as well as your answer. (If you did the problem off-line, you can also manually enter the time spent.)

—Flag the question as a guess. This is especially helpful when you’re doing a set of problems and want to review your guesses more carefully afterwards.

—Tag the question for re-do. You have three options: Yes, No, and Maybe. Later, you can sort your problem list to look at all of the ones you’ve tagged Yes, for example.

After you’ve submitted an answer, take a look at the explanation (if you have access). There are written explanations for every OG13 and OG12 quant problem, as well as every OG13 sentence correction problem. There are also more than 300 video explanations across all problem types—DS, PS, RC, CR, and SC—from OG13.

If you make your own Tracker, you’ll need a row for every problem in whatever books you’re going to use. You should be able to label the source book, question type, and problem number. You’ll also want to include columns for time spent, whether you answered the problem correctly, whether it was a guess, and whether you want to mark it for later review.

Analyze Your Stats

As you use Navigator, it will keep track of all of your statistics: the time you spend on each problem, whether you answered it correctly or incorrectly, and so on. If you use your own Tracker, make sure to record these statistics.

Review Your Answers
Within Navigator, the Review Your Answers button will show you a list of all of the problems you’ve completed in the system. You can sort by the basics (book, question number, topic) and you can also sort by other interesting metrics, such as whether you got the question right, how much time you spent, whether you flagged it as a Guess or Do Again problem, and even how hard the problem is. (We’ve tagged all of the problems with one of four difficulty levels based on how our students have collectively done on that problem.)

If you make your own Tracker, use Excel so that you can sort the data by any column. You won’t get the difficulty data, but you can track everything else yourself.

Statistics
The Statistics button will take you to a new window that summarizes your stats across all of the major topic areas and question types (using the same categories we use in our books). You can choose to display the data on a graph or in a table.

The graph feature is particularly neat. You can click on any of the boxes or circles in the graph to dive down into that data set, all the way down to the individual problems.

You can use this data to discover, for example, that you tend to spend too much time on Rates & Work problems on the whole. Your stats might tell you that, while Number Properties problems are okay overall, you’re really good at Odd, Even, Positive, and Negative, but you’re struggling with Divisibility and Prime.

All of these categories correspond to specific chapters in our books, so you can use the data to help you know what topics you need to review. (And the books themselves list OG problems by content area, so once you’re done reviewing, you can pick out a couple of new problems to try.)

Timing

You may discover that you have timing problems—most people do, in fact. I linked to two important articles in the first half of this series. Make sure to read both of those articles first. Then, learn all about Time Management for the GMAT.

If you are still struggling to cut yourself off (and we all struggle with this at least a little bit!), take a look at the But I Studied This! article and learn how to cut yourself off.

Final Words

You’re going to feel like you’re drowning in information while you’re studying for the GMAT. Make your life at least somewhat easier by tracking what you do. Your analysis of those stats will help you to prioritize your study, so that you don’t find yourself spending 3 hours on a topic that’s already a strength for you (or, worse, not having any idea what to do next because you’re not sure what your weaknesses are).

Finally, we’re always looking for good ideas about features to add to Navigator. If you have any bright ideas, please share with us in the Comments section!

data-sufficiencySome Data Sufficiency questions present you with scenarios: stories that could play out in various complicated ways, depending on the statements. How do you get through these with a minimum of time and fuss?

Try the below problem. (Copyright: me! I was inspired by an OG problem; I’ll tell you which one at the end.)

* “During a week-long sale at a car dealership, the most number of cars sold on  any one day was 12. If at least 2 cars were sold each day, was the average daily number of cars sold during that week more than 6?

“(1) During that week, the second smallest number of cars sold on any one day was 4.

“(2) During that week, the median number of cars sold was 10.”

First, do you see why I described this as a “scenario” problem? All these different days… and some number of cars sold each day… and then they (I!) toss in average and median… and to top it all off, the problem asks for a range (more than 6). Sigh.

Okay, what do we do with this thing?

Because it’s Data Sufficiency, start by establishing the givens. Because it’s a scenario, Draw It Out.

Let’s see. The “highest” day was 12, but it doesn’t say which day of the week that was. So how can you draw this out?

Neither statement provides information about a specific day of the week, either. Rather, they provide information about the least number of sales and the median number of sales.

The use of median is interesting. How do you normally organize numbers when you’re dealing with median?

Bingo! Try organizing the number of sales from smallest to largest. Draw out 7 slots (one for each day) and add the information given in the question stem:

Screen Shot 2014-04-10 at 12.37.53 PM

Now, what about that question? It asks not for the average, but whether the average number of daily sales for the week is more than 6. Does that give you any ideas for an approach to take?

Because it’s a yes/no question, you want to try to “prove” both yes and no for each statement. If you can show that a statement will give you both a yes and a no, then you know that statement is not sufficient. Try this out with statement 1

(1) During that week, the least number of cars sold on any one day was 4.

Draw out a version of the scenario that includes statement (1):

Screen Shot 2014-04-10 at 12.38.22 PM

Can you find a way to make the average less than 6? Keep the first day at 2 and make the other days as small as possible:

Screen Shot 2014-04-10 at 12.38.58 PM

The sum of the numbers is 34. The average is 34 / 7 = a little smaller than 5.

Can you also make the average greater than 6? Try making all the numbers as big as possible:

Screen Shot 2014-04-10 at 12.39.24 PM

(Note: if you’re not sure whether the smallest day could be 4—the wording is a little weird—err on the cautious side and make it 3.)

You may be able to eyeball that and tell it will be greater than 6. If not, calculate: the sum is 67, so the average is just under 10.

Statement (1) is not sufficient because the average might be greater than or less than 6. Cross off answers (A) and (D).

Now, move to statement (2):

(2) During that week, the median number of cars sold was 10.

Again, draw out the scenario (using only the second statement this time!).

Screen Shot 2014-04-10 at 12.39.59 PM

Can you make the average less than 6? Test the smallest numbers you can. The three lowest days could each be 2. Then, the next three days could each be 10.

Screen Shot 2014-04-10 at 12.40.21 PM

The sum is 6 + 30 + 12 = 48. The average is 48 / 7 = just under 7, but bigger than 6. The numbers cannot be made any smaller—you have to have a minimum of 2 a day. Once you hit the median of 10 in the middle slot, you have to have something greater than or equal to the median for the remaining slots to the right.

The smallest possible average is still bigger than 6, so this statement is sufficient to answer the question. The correct answer is (B).

Oh, and the OG question is DS #121 from OG13. If you think you’ve got the concept, test yourself on the OG problem.

 

Key Takeaway: Draw Out Scenarios

(1) Sometimes, these scenarios are so elaborate that people are paralyzed. Pretend your boss just asked you to figure this out. What would you do? You’d just start drawing out possibilities till you figured it out.

(2) On Yes/No DS questions, try to get a Yes answer and a No answer. As soon as you do that, you can label the statement Not Sufficient and move on.

(3) After a while, you might have to go back to your boss and say, “Sorry, I can’t figure this out.” (Translation: you might have to give up and guess.) There isn’t a fantastic way to guess on this one, though I probably wouldn’t guess (E). The statements don’t look obviously helpful at first glance… which means probably at least one of them is!

 

DropScoreI’m reviving an old article I first wrote five years ago (time flies!) because the topic is so important. I hope that no one ever again experiences a significant score drop on the real test (or even a practice one!), but the reality is that this does happen. The big question: now what?

If this happens to you, the most important thing to do next is figure out why this happened. If you can figure out why, then you may be able to do something to prevent a score drop from happening again.

 

1: Official Test Conditions

Did you take your practice tests under official test conditions? Did you:

  • Do the essay and IR sections?
  • Take only two 8-minute breaks (the first between IR and quant, the second between quant and verbal)?
  • Complete the test in one sitting (e.g., you didn’t do the verbal section later that evening or the next day)?
  • Pause the test, look at books or notes, eat and drink during the test, or do anything else that wouldn’t be allowed on test day

If you did not take your practice tests under official testing conditions, then your practice scores were likely inflated—possibly just a little or possibly a lot, depending upon how far you were from official test conditions. If your practice test scores were inflated, then the bad news is that your scoring level wasn’t as good as you thought it was. In other words, your official test didn’t represent as much of a drop as you first thought (and, possibly, the official test didn’t represent any drop at all).

While this is not great news, it is crucial to know, because it tells you what the problem is. You need to figure out in which areas you’re falling short and do what you need to do (math, grammar, time management, problem-solving skills) in order to improve. (And don’t forget to take tests under official conditions in future, so that you get a true picture of your current scoring level.)

2: Timing

Mismanaged timing might be the most common cause of big score drops on the test. If your scores keep jumping up and down on practice tests and you’re not sure why, your timing may be the culprit.

Timing is so crucial because of certain consequences that can kill your score. You tend to make more careless mistakes when you’re rushing. You may get multiple questions wrong in a row. You may run out of time entirely before the section is over. All of these things will have a negative impact on your score.

There are two major categories for mismanaged timing: too slow and too fast. These two categories lead to three common scenarios:

  1. Run out of time before the section is over
  2. Finish the section with lots of time left
  3. Finish just on time—but a review of the timing patterns shows that you spent too long on some, then rushed on others to catch up. (We call this “up and down timing.”)

The vast majority of students who mismanage time badly enough to experience a big score drop will do so by going too slowly at some point on the test and, consequently, either running out of time with questions left or being forced to move too quickly at other points, thereby increasing the error rate.
Continue Reading…

gmat-quant-strategySo you’ve been told over and over that guessing is an important part of the GMAT. But knowing you’re supposed to guess and knowing when you’re supposed to guess are two very different things. Here are a few guidelines for how to decide when to guess.

But first, know that there are two kinds of guesses: random guesses and educated guesses. Both have their place on the GMAT. Random guesses are best for the questions that are so tough, that you don’t even know where to get started. Educated guesses, on the other hand, are useful when you’ve made at least some progress, but aren’t going to get all the way to an answer in time.

Here are a few different scenarios that should end in a guess.

Scenario 1: I’ve read the question twice, and I have no idea what it’s asking.

This one is pretty straightforward. Don’t worry about whether the question is objectively easy or difficult. If it’s too hard for you, it’s not worth doing. In fact, it’s so not worth doing that it’s not even worth your time narrowing down answer choices to make an educated guess. In fact, if it’s that difficult, it may even be better for you to get it wrong!

To make the most of your random guesses, you should use the same answer choice every time. The difference is slight, but it does up your odds of getting some of these random guess right.

Scenario 2: I had a plan, but I hit a wall.

Often, when this happens, you haven’t yet spent 2 minutes on the problem. So why guess? Maybe now you have a better plan for how to get to the answer. I know this is hard to hear, but don’t do it! To stay on pace for the entire section, you have to stay disciplined and that means that you only have one chance to get each question right.

The good news is that no 1 question you get wrong will kill your score. But, 1 question can really hurt your score if you spend too long on it! Once you realize that your plan didn’t work, it’s time to make an educated guess. You’ve already spent more than a minute on this question (hopefully not more than 2!), and you probably have some sense of which answers are more likely to be right. Take another 15 seconds (no more!) and make your best educated guess.

Scenario 3: I got an answer, but it doesn’t match any of the answer choices.

This is another painful one, but it’s an almost identical situation to Scenario 2. It means you either made a calculation error somewhere along the way, or you set the problem up incorrectly to begin with. In an untimed setting, both of these problems would have the same solution: go back over your work and find the mistake. On the GMAT, however, that process is too time-consuming. Plus, even once you find your mistake, you still have to redo all the work!

Once again, though it might hurt, it’s still in your best interest to let the question go. If you can narrow down the answer choices, great (though don’t spend longer than 15 or 20 seconds doing so). If not, don’t worry about it. Just make a random guess and vow to be more careful on the next one (and all the rest after that!).

Scenario 4: I checked my pacing chart and I’m more than 2 minutes behind.

Pacing problems are best dealt with early. If you’re more than 2 minutes behind, don’t wait until another 5 questions have passed and you realize you’re 5 minutes behind. At this point, you want to find a question in the next 5 that you can guess randomly on. The quicker you can identify a good candidate to skip, the more time you can make up.

This is another scenario where random guessing is best. Educated guessing takes time, and we’re trying to save as much time as possible. Look for questions that take a long time to read, or that deal with topics you’re not as strong in, but most importantly, just make the decision and pick up the time.

Wrap Up

Remember, this test is not like high school exams; it’s not designed to have every question answered. This test is about consistency on questions you know how to do. Knowing when to get out of a question is one of the most fundamental parts of a good score. The better you are at limiting time spent on really difficult questions, the more time you have to answer questions you know how to do.

Plan on taking the GMAT soon? We have the world’s best GMAT prep programs starting all the time. And, be sure to find us on Facebook and Google+, and follow us on Twitter!

gmat-scholarshipDo you promote positive social change? Do you work for a non-profit? Manhattan Prep is offering special full tuition scholarships for up to 16 individuals per year (4 per quarter) who will be selected as part of Manhattan GMAT’s Social Venture Scholars program. SVS program provides selected scholars with free admission into one of Manhattan GMAT’s live online Complete Courses (a $1290 value).

These competitive scholarships are offered to individuals who (1) currently work full-time in an organization that promotes positive social change, (2) plan to use their MBA to work in a public, not-for-profit, or other venture with a social-change oriented mission, and (3) demonstrate clear financial need. The Social Venture Scholars will all enroll in a special online preparation course taught by two of Manhattan GMAT’s expert instructors within one year of winning the scholarship.

The deadline is fast approaching!: March 28, 2014! 

Learn more bout the SVS program and apply to be one of our Social Venture Scholars here.

manhattan gmat international ron purewal

Manhattan GMAT’s Live Online Spring P2 Course is a comprehensive GMAT course designed specifically for high-achieving, international students looking to earn an MBA from a top business school. Taught by famed GMAT instructor, Ron Purewal, our Live Online Spring P2 Course will be hosted in the early morning (5:30AM-8:30AM PDT) from Silicon Valley, California.

We’re inviting students from all around the world to join, with the hope that this unique time will fit more conveniently into international students’ schedules. The course aims to teach mastery of GMAT content and the test-taking skills and strategies that are necessary to conquering every question type with confidence.

The Live Online Spring P2 Course with Ron Purewal begins April 16th, 2014 and includes:

• 54 hours of class time & coaching – at a time specifically selected to best support international GMAT test-takers.

• Strategy Guides that equip you for the entire GMAT: math and verbal theory, problem solving techniques, essential formulae, and hundreds of examples

• Every Official Guide for GMAT Review (that’s over 1400 real GMAT problems!)

• Foundational math and verbal primers—including books, question banks, and online workshops to help you review

• Full Integrated Reasoning training, plus an online bank of questions for additional practice
• Six full-length Computer Adaptive Practice Tests, designed in-house by our veteran instructors to simulate the GMAT’s uniquely adaptive format
• Detailed practice dashboards that show you how you’re performing (including stats on accuracy, speed, and difficulty level) across every specialized math and verbal topic
• On Demand Class Recordings so you can review course concepts anytime
• eBook downloads of every Manhattan GMAT Strategy Guide, accessible on your iPad, Nook, smartphone, or other compatible mobile device
• Challenge problems, interactive labs, essay grading software, and dozens of additional resources

Space is limited and filling quickly, so be sure to register for Ron Purewal’s upcoming Live Online GMAT Course at this special international time before it’s too late.

Not sure if this class is right for you? Attend the first session for free and try it out before signing up for the complete program.

 

Five-Steps-Email-croppedAre you ready for the 2014–2015 MBA application season?

Join Manhattan Prep, mbaMission, and Poets & Quants for a free, five-part webinar series to help you prepare!

Three leaders in the MBA admissions space—Poets & QuantsmbaMission and Manhattan Prep—are banding together to ensure that you will be ready for the 2014–2015 MBA admissions season. Together, we are launching a free, five-part webinar series entitled “Five Steps to Business School Acceptance”! In each of the first four sessions, a senior consultant from mbaMission will address and explain a different significant admissions issue, while Poets & Quants’ John Byrne serves as host, moderating any questions and answers. Then, an expert from Manhattan Prep will present a challenging GMAT issue, offering insight, advice and more. The fifth and final session consists of a discussion panel with current admissions officers, sharing their thoughts and answering questions about the upcoming admissions season.

We hope you will join us for this special series. Please sign up for each session separately via the links below—space is limited.

Session 1: March 19, 2014 - Watch the recording of our first session here to see what all of the buzz is about! 

Session 2: April 2, 2014 - Click Here to watch the recording of Choosing the Right B-School and Advanced Quant

Session 3: April 16, 2014 - What Can I Do with My MBA? and Getting the Most Out of Your Practice GMAT Exams

Session 4: April 30, 2014 - Essay Writing Workshop and Advanced Sentence Correction

Session 5: May 14, 2014 - Questions and Answers with MBA Admissions Officers

Do you have questions for our GMAT and MBA admissions experts? Ask them in the comments below, and we will do our best to answer them in the Q&A sessions following each presentation, or reach out to use on social using the hashtag #fivesteps.