We’re going to kill two birds with one stone in this week’s article.
Inference questions pop up on both Critical Reasoning (CR) and Reading Comprehension (RC), so you definitely want to master these. Good news: the kind of thinking the test-writers want is the same for both question types. Learn how to do Inference questions on one type and you’ll know what you need to do for the other!
That’s actually only one bird. Here’s the second: both CR and RC can give you science-based text, and that science-y text can get pretty confusing. How can you avoid getting sucked into the technical detail, yet still be able to answer the question asked? Read on.
Try this GMATPrep® CR problem out (it’s from the free practice tests) and then we’ll talk about it. Give yourself about 2 minutes (though it’s okay to stretch to 2.5 minutes on a CR as long as you are making progress.)
“Increases in the level of high-density lipoprotein (HDL) in the human bloodstream lower bloodstream cholesterol levels by increasing the body’s capacity to rid itself of excess cholesterol. Levels of HDL in the bloodstream of some individuals are significantly increased by a program of regular exercise and weight reduction.
“Which of the following can be correctly inferred from the statements above?
“(A) Individuals who are underweight do not run any risk of developing high levels of cholesterol in the bloodstream.
“(B) Individuals who do not exercise regularly have a high risk of developing high levels of cholesterol in the bloodstream late in life.
“(C) Exercise and weight reduction are the most effective methods of lowering bloodstream cholesterol levels in humans.
“(D) A program of regular exercise and weight reduction lowers cholesterol levels in the bloodstream of some individuals.
“(E) Only regular exercise is necessary to decrease cholesterol levels in the bloodstream of individuals of average weight.”
Got an answer? (If not, pick one anyway. Pretend it’s the real test and just make a guess.) Before we dive into the solution, let’s talk a little bit about what Inference questions are asking us to do.
Inference questions are sometimes also called Draw a Conclusion questions. I don’t like that title, though, because it can be misleading. Think about a typical CR argument: they usually include a conclusion that is…well…not a solid conclusion. There are holes in the argument, and then they ask you to Strengthen it or Weaken it or something like that.
The newest GMAT Strategy Guides have hit the shelves! We’re really excited about these new books, the perfect stocking stuffers to make all of your dreams come true. (Well…your GMAT-related dreams, anyway.)
Yesterday, we talked about the Quant Guides and today I’ve got the Verbal scoop for you. Let’s start with Sentence Correction.
The SC Guide begins with a new strategy chapter that discusses our 4-Step SC Process and lays out drills that you can do to get better at such skills as the First Glance and Finding a Starting Point. We’ve also significantly expanded the Subject-Verb Agreement chapter to include a full treatment of Sentence Structure, an area that has been becoming much more commonly tested on the GMAT.
We’ve added important segments to Modifiers, Parallelism, and Verbs and we’ve woven relevant Meaning topics into every chapter in the book.
Finally, we’ve streamlined the Idioms material. The main chapter contains a strategy for tackling idioms as well as the most commonly tested idioms found on the GMAT. A separate appendix contains the less-commonly-tested idioms. We recommend taking the time to memorize the ones listed in the main chapter, but to use the appendix more as a resource to look up the correct idiom when you struggle with a particular problem. (It’s impossible to memorize every idiom in a language; there are thousands, if not tens of thousands!)
What about RC and CR?
Glad you asked! Our Reading Comprehension Guide was re-written from scratch. We’ve streamlined the process for reading passages and added lessons designed to help you wade through these dense passages and extract the kernels you need to answer questions. We’ve also expanded our lessons for each question type and provided you with end-of-chapter cheat sheets that summarize what to do for each question type and what common traps to avoid. (I’m most excited about this book; students often complain that RC is hard to study, and I’m hoping that this book will change your minds!)
Of all of the books, Critical Reasoning has changed the least, although we did add more information about Fill-In-The-Blank question types. This Guide also provides you with end-of-chapter cheat sheets that summarize how to recognize each type of question, what to look for in the argument, what kind of characteristics the right answer needs to possess, and how to spot the most common trap answers.
What is the best way to use the books?
Here’s how we typically study each topic in class:
First, we learn how to use the SC Process and we discuss the main topics being tested (grammar and meaning); these correspond to chapters 1 and 2 of the book. Then, we work through one new chapter a week, starting with Chapter 3 (Sentence Structure). The order of chapters in the book is the same order we use in class.
You can use the same approach mentioned for quant (in the first half of this article): do some end-of-chapter problems first to see what your skills are. If you know that you don’t really know this material, then you can also skip this step. After you’ve finished a chapter, try some of those end-of-chapter problems to ensure that you did actually internalize the concepts that you just learned. Then, if you have the OG books, follow up with some questions from the OG Problem Sets, located in your Manhattan Prep Student Center.
The class contains three RC lessons. First, we learn how to read. Bet you thought you already knew how, didn’t you?
Of course you do know how to read, but the way you read in the real world may not work very well on the GMAT. You’ll learn a new way to deal with the short timeframe we’re given on the test. After that, you’ll learn how to handle General questions, the ones for which you need to wrap your brain around the main ideas of the passage.
Then, you’ll move on to Specific Questions, including Detail, Inference, and Purpose questions. The test writers are asking us to do something a bit different for each one, so you’ll need to learn how to recognize each type in the first place and then how to handle it.
In class, we finish off with a Challenging RC lesson. You can create something similar for yourself by tackling harder and harder OG passages.
Critical Reasoning begins with a thorough treatment of argument building blocks and the 4-Step CR Process. After that, you’ll learn about each question type (do actually use the order presented in the book). Pay attention to what the book says about frequency of each type; some types are much more common than others (and those types should obviously get more of your attention).
For both CR and RC, tear out or photo-copy the cheat sheets and use them to quiz yourself. Alternatively, put the material onto flash cards yourself (the act of rewriting the material will help you to remember it better!) and drill while you’re sitting on the subway or waiting for that meeting to start.
Is that all I need to do?
That will certainly keep you busy for a while. As you get further into your studies, note that you also need to lift yourself to the 2nd Level of GMAT Study. Yes, of course, there are lots of facts, formulas, and rules to memorize, and your brain will be focused on those areas at first. It’s crucial, however, for you to learn the various strategies presented in our Guides, as well as your own decision-making strategies based on your own strengths and weaknesses, and timing strategies.
In short, get ready to make a commitment. Think of studying for the GMAT as a university-level course: you’re going to spend hours every week for about 3 to 4 months to get ready for this test. With a solid plan, you’ll achieve your goals.
Studying for the GMAT? Take our free GMAT practice exam or sign up for a free GMAT trial class running all the time near you, or online. And, be sure to find us on Facebook and Google+,LinkedIn, and follow us on Twitter!
My last two articles (part 1 and part 2) gave you some advanced tools to analyze deductive reasoning. Now it’s time to dive into the wonderful world of inductive reasoning, which appears much more often, especially in the following GMAT question types:
• Fill in the blank
• Identify the role
• Identify the overall reasoning
• Identify the conclusion
• Mimic the reasoning (sometimes)
According to Wikipedia:
“Inductive reasoning (as opposed to deductive reasoning) is reasoning in which the premises seek to supply strong evidence for (not absolute proof of) the truth of the conclusion. While the conclusion of a deductive argument is supposed to be certain, the truth of an inductive argument is supposed to be probable, based upon the evidence given.”
Therefore, in inductive arguments, conclusions are a matter of opinion, some more strongly supported than others.
Beyond the basics: P.O.S.E.
First, from class and your own study, you should be able to DECONSTRUCT arguments–in other words, identify the background, conclusion, premises, counterpoint, and counter premises of all inductive arguments. Our books cover that skill thoroughly if you need more work.
Next, you should learn to categorize each conclusion by type.
Fortunately, the GMAT uses only a few basic argument patterns, with similar assumptions and a limited number of ways to strengthen or weaken those assumptions. If you can spot and name those patterns, you’re well on your way to drastically improving your CR score.
My last article discussed the difference between inductive and deductive arguments. Today’s article will focus mostly on the rules of deductive arguments. I promise to nerd out on inductive reasoning in later articles.
Here’s a quick quiz on the difference between inductive and deductive logic: http://www.thatquiz.org/tq/previewtest?F/Z/J/V/O3UL1355243858
To review: In a deductively “valid” argument, if all the premises are true, the conclusion must also be true, with 100% certainty. Luckily, on the GMAT, we should usually act as if the premises of an argument are true, especially when the question specifies, “the statements above are true.”
Deductive reasoning shows up most often on inference (aka “draw a conclusion”) questions and “mimic the reasoning” questions, but it often appears on other types of questions, and even on reading comprehension!
On inference questions, the correct answer will usually be deductively valid (or very very strong, inductively). An incorrect answer will be deductively invalid, with some significant probability that it could be false.
What follows are most of the formal rules of deductive reasoning (from a stack of logic textbooks I have on my shelf), with examples from the GMAT. For shorthand, I’ll label the arguments with a “P” for premise and a “C” for conclusion:
Remember: these are not the same kind of conclusions (opinions) you’ll see on strengthen and weaken questions. Deductive conclusions are deductively “valid” facts that you can derive with 100% certainty from given premises.
EASY STUFF: Simplification/conjunction (“and” statements)
This is kind of a “duh” conclusion, but here goes: If two things are linked with an “and,” then you know each of them exist. Conversely, if two things exist, you can link them with an “and.”
P) A and B
C) Therefore, A
C) Therefore, A and B
P) Bill is tall and was born in Texas.
P) Bill rides a motorcycle.
C) Therefore, Bill was born in Texas (simplification).
C) Therefore, at least one tall person named Bill was born in Texas and rides a motorcycle (conjunction).
CAUTION: Fallacies ahead!!
Don’t confuse “and” with “or.” (More about this later.) More importantly, don’t confuse “and” with causality, condition, or representativeness. Bill’s tallness probably has nothing to do with Texas, so keep an eye out for wrong answers that say, “Bill is tall because he was born in Texas” or “Most people from Texas ride motorcycles.”
MEDIUM STUFF: Disjunctive syllogism (“or” statements)
With “or” statements, if one thing is missing, the other must be true.
P) A or B
P) not B (shorthand: ~B)
C) Therefore, A
P) We will go to the truck rally or to a Shakespeare play
P) We won’t go to the Shakespeare play.
C) Therefore, we will go to the truck rally.
CAUTION: Fallacies ahead!!
Unlike in the real world, “or” statements do not always imply mutual exclusivity, unless the argument explicitly says so. For example, in the above arguments, A and B might both be true; we might go to a play and go to the movies. Yes, really. A wrong answer might say “We went to a play, so we won’t go to the movies.” This error is called “affirming the disjunct.”
P) A or B
C) Not A
To see this in action, check out your The Official Guide for GMAT Review 13th Edition, by GMAC®*, question 41. This argument opens with an implied “or” statement:
“Installing scrubbers in smokestacks and switching to cleaner-burning fuel are the two methods available to Northern Power…”
The author here incorrectly assumes that by using one method, Northern Power can’t use both methods at the same time. Question 51 does the same thing; discuss it in the comments below?
TOUGH STUFF: Fun with conditional statements
This is important! Keep a sharp eye out for statements that can be expressed conditionally and practice diagramming them. Look for key words such as “if,” “when,” “only,” and “require.”
I use the symbol “–>” to express an if/then relationship, and a “~” to express the word “not.” Use single letters or abbreviations to stand in for your elements.
We’ve been on a CR kick lately! In the first two parts of this series, we talked about how to tackle Fill in the Blank and Complete the Passage questions. This time, I’ve got something different for you: a question that looks very familiar at first glance but turns a bit… well, weird.
Let’s try it before I say anything more. This GMATPrep© problem is from the two free exams that come with the GMATPrep software. Give yourself about 2 minutes (though it’s okay to stretch to 2.5 minutes on a CR as long as you are making progress.)
“On of the limiting factors in human physical performance is the amount of oxygen that is absorbed by muscles from the bloodstream. Accordingly, entrepreneurs have begun selling at gymnasiums and health clubs bottles of drinking water, labeled “SuperOXY,” that has extra oxygen dissolved in the water. Such water would be useless in improving physical performance, however, since the amount of oxygen in the blood of someone who is exercising is already more than the muscle cells can absorb.
Which of the following, if true, would serve the same function in the argument as the statement in boldface?
“(A) world-class athletes turn in record performances without such water
“(B) frequent physical exercise increases the body’s ability to take in and use oxygen
“(C) the only way to get oxygen into the bloodstream so that it can be absorbed by the muscles is through the lungs
“(D) lack of oxygen is not the only factor limiting human physical performance
“(E) the water lost in exercising can be replaced with ordinary tap water”
Step 1: Identify the Question
The boldface font is immediately obvious, of course. Boldface denotes a Describe the Role question.
The question stem does have one little idiosyncrasy, though: it asks what answer would serve the same function. Normally, Role questions ask what function the boldface statement plays in the argument. The question stem also contains “if true” wording, which we normally see on Strengthen, Weaken, or Discrepancy (paradox) questions.
Glance at the answers. Notice anything? This is not what Role answers typically look like! Usually they say something such as “The statement provides evidence supporting the author’s claim” or similar.
What’s going on here? Read the argument.
Step 2: Deconstruct the Argument
Here’s what I thought and wrote while I did the problem. Your own thought process won’t be exactly the same as mine and, of course, your notes will probably look quite different, since we all have our own ways of abbreviating things. (Note: R = role; note that I put a question mark next to it because I wasn’t 100% sure what was actually going on).
So back to that weird question stem. If this were just a straight Role question, then what would the answer be? The boldface statement is support for the conclusion; it’s a premise.
But what’s the goal for this question?
Step 3: State the Goal
The answers don’t describe the existing boldface statement. Rather, they contain new facts that we’re supposed to accept as true. Further, the question asked us to find an answer that “would serve the same function” as the original statement.
What function did the original statement serve? Aha! The original statement served as a premise to support the conclusion. So we need to find another statement that serves that same purpose.
Will it support the conclusion in exactly the same way? I’m really not sure. (Seriously! When I first saw this question, I didn’t know!) So I’m going to keep an open mind and look for anything that could support the conclusion in general.
Work from Wrong to Right
The correct answer is (C).
Interesting. We just learned something new. Most Describe the Role (or Boldface) questions ask us to describe the role of the given statement. We might be asked, though, to demonstrate our knowledge of the role by finding a different, completely new statement that serves the same role as the original statement in the argument.
What do we have to do? We have to “decode” the original statement (in the above case, we had a premise supporting the conclusion) and then we have to find another statement that could also serve as a premise.
That new premise might be really different from the original premise. In this problem, the original premise focused on the oxygen already in our blood. The new premise, answer (C), provided a different piece of the puzzle: we have to take oxygen in through our lungs in order to get that oxygen into the bloodstream. Either piece of information serves to support the idea that OXY is useless, but each does so in different ways.
Take-aways for “Same Function As” Role Questions:
(1) The standard task on role questions is to describe the role of the statement given in the argument.
(2) You might see a variation on this standard task: you may be asked to find a new statement that plays the same role as the original.
(3) This new statement may discuss a different aspect of the argument. That’s perfectly all right as long as the statement overall plays the same role as the original boldface statement.
* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.
In honor of the final season of Breaking Bad, we decided to put together our ultimate Breaking Bad GMAT quiz. Those of you who fall in the overlapping section of the “Breaking Bad Fan” “GMAT student” Venn diagram should test your skills below… yo!
1. Data Sufficiency
Does x+4 = Walter White?
(1) x+4 is the danger
(2) x+4 is the one who knocks
A. Statement (1) ALONE is sufficient, but statement (2) ALONE is not sufficient
B. Statement (2) ALONE is sufficient, but statement (1) ALONE is not sufficient
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient
D. EACH statement ALONE is sufficient
E. Statement (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data are needed
2. Discrete Quant
The front portion of Walter White’s Roof is a 7 ‘ by 15’ rectangle. If the diameter of a pizza is 22”, what is the approximate area of the shaded region of this diagram?
A. 13,600 inches sq.
B. 14,740 inches sq.
C. 15,120 inches sq.
D. 15,500 inches sq.
E. 16,640 inches sq.
3. Critical Reasoning
Today, Walter White will cook 100 pounds of methamphetamine.
This argument is flawed primarily because:
A. Cooking methamphetamine presents a moral dilemma for Walter White.
B. Walter White has to prioritize the needs of his wife and children and be a better father.
C. Walter has already paid for his cancer treatment and no longer needs to cook methamphetamine.
D. There is a fly in the laboratory.
E. He was told not to cook that day and is obeying his instructions.
4. Critical Reasoning
Hank’s collection of rocks includes over 400 different items. Hank’s rock collection is clearly the most impressive in New Mexico.
This argument is flawed primarily because:
A. Rock collections are not judged by the total number of rocks but by the rarity of each item included.
B. Rock collections are not impressive to anyone.
C. Hank’s rock collection is a metaphor and therefore cannot be judged against other rock collections.
D. Hank’s wife stole most of the rocks and it is therefore ineligible for any superlatives.
E. They aren’t rocks, they are minerals.
5. Discrete Quant
Walter Junior eats 3 eggs for breakfast every morning. Given that Walter Junior never misses breakfast, how many eggs does Walter Junior consume in March?
Answers are after the jump…
Recently, we published the Master Resource List for Critical Reasoning, but I had to link to an older version of a Boldface explanation because I hadn’t yet written an article using the new process. I’m remedying that gap now. (Note: technically, these are called Describe the Role questions.)
Try this problem out! Give yourself about 2 minutes (though it’s okay to stretch to 2.5 minutes on a long one like this as long as you are making progress.)
Consumer advocate: It is generally true, at least in this state, that lawyers who advertise a specific service charge less for that service than lawyers who do not advertise. It is also true that each time restrictions on the advertising of legal services have been eliminated, the number of lawyers advertising their services has increased and legal costs to consumers have declined in consequence. However, eliminating the state requirement that legal advertisements must specify fees for specific services would almost certainly increase rather than further reduce consumers’ legal costs. Lawyers would no longer have an incentive to lower their fees when they begin advertising and if no longer required to specify fee arrangements, many lawyers who now advertise would increase their fees.
In the consumer advocate’s argument, the two portions in boldface play which of the following roles?
(A) The first is a generalization that the consumer advocate accepts as true; the second is presented as a consequence that follows from the truth of that generalization.
(B) The first is a pattern of cause and effect that the consumer advocate argues will be repeated in the case at issue; the second acknowledges a circumstance in which that pattern would not hold.
(C) The first is a pattern of cause and effect that the consumer advocate predicts will not hold in the case at issue; the second offers a consideration in support of that prediction.
(D) The first is evidence that the consumer advocate offers in support of a certain prediction; the second is that prediction.
(E) The first acknowledges a consideration that weighs against the main position that the consumer advocate defends; the second is that position.
Step 1: Identify the Question
The argument itself contains the most common clue for a Describe the Role question: boldface font in the text. This clue doesn’t always exist but it is usually there. The question stem also signals the type by asking for the role played by the two portions in boldface.
Step 2: Deconstruct the Argument
All right, this is a Role question. The argument will contain a conclusion, and the boldface portions will relate to the conclusion in one of three broad ways:
- The boldface text could be the conclusion.
- The boldface text could support the conclusion.
- The boldface text could be anything else (including neutral background), though most commonly it will be either counter-premise or a counter-conclusion.
Which CR question type drives you crazy? Boldface? Find the Assumption? Inference?
I’ve put together what I’m calling the Master Resource List for this question type. A couple of disclaimers. First, this list includes only free resources, no paid ones. There are a lot of good resources out there that cost some money”they’re just not on this list!
Second, this list is limited to my own articles. I’m not trying to claim that only my articles are good enough to make such a list”far from it. I’m most familiar with my own articles, so that’s what I’m using. (And, okay, I will admit that I think the ManhattanGMAT CR process is the best one out there. But I’m biased. : ) )
The CR Process
Before you dive into individual question types, it’s critical to know the overall CR process. A few key notes:
- There 4 major and 5 minor question sub-types* and each one has its own particular technique details.
- Your job is to learn the overall process / strategy for CR as well as the techniques specific to each question sub-type.
* Every now and then, a question pops up that doesn’t quite fit one of the 9 main categories. There are exceptions to every rule in the universe.
In order to master CR, you should be able to answer the following questions about each question type:
- How do I recognize this question type?
- What kind of information should I expect to find in the argument, based on this question type? What kind of information is going to be the most important?
- What is the goal for this question type? What characteristics must the correct answer have?
- What kinds of traps will be set for me? What are the common wrong answer types for this question type?
Many a true word is said in jest.—I don’t know, but I heard it from my mother.
I think that Critical Reasoning is my favorite part of the exam because it is the purest of the pure. I’ve written before that the GMAT is an aptitude test rather than a knowledge test. On the simplest level, in both the quant and the verbal, the exam tests a logic system: be specific, don’t assume, and don’t rationalize. Nowhere is this more true than in Critical Reasoning—there is no mathematical foundation work nor are there grammar rules. As Gertrude Stein used to say, There is no there, there. Of course, she was talking about Oakland. . .fill in your own joke. When I’m being* mean to students, I say, If you know what all the words mean, you should get them all right.
But students don’t get them all right. Even those who know what all the words mean. Why is that? Because people think. They assume, they rationalize, and they inject opinions. Why is this bad? Because it’s a game. Critical Reasoning doesn’t take place in reality. Here’s an analogy I thought up all by myself, so it isn’t in the Strategy Guide: Critical Reasoning bears the same relationship to reality that Monopoly does. When you play Monopoly, you don’t think about how reasonable free parking or building hotels is, you exploit the rules. It’s the same thing. A lot of OG arguments involve medical issues, but you hardly ever care whether people live or die because that’s usually not the conclusion. Play the game.
As a by the way, if students struggle with the CR, it’s often half of their trouble in the quant. Folks are not specific; they read the question or the given incorrectly. And they don’t recognize the types and patterns. In other words, they don’t play that game. However, folks fail to notice these mistakes because they are too consumed with worry about their math foundations. Conversely, engineers with strong foundations also suffer here, especially in the DS because they try to use brute mathematical force instead of playing the game. It is a behavioral problem. People don’t do; they think. Don’t think—much like in life, it only gets you into trouble.
Recently, I published an article challenging those going for a 750+ to answer a certain quant question in 30 seconds. I received a lot of positive feedback about that article “ and requests for more of the same.
I’m happy to oblige: here’s a GMATPrep CR problem. The normal timeframe is about 2 minutes “ but if you’re going for a 750+, you’d need to be able to answer something like this much more quickly.
Correctly measuring the productivity of service workers is complex. Consider, for example, postal workers: they are often said to be more productive if more letters are delivered per postal worker. But is this really true? What if more letters are lost or delayed per worker at the same time that more are delivered?
The objection implied above to the productivity measure described is based on doubts about the truth of which of the following statements?
(A) Postal workers are representative of service workers in general.
(B) The delivery of letters is the primary activity of the postal service.
(C) Productivity should be ascribed to categories of workers, not to individuals.
(D) The quality of services rendered can appropriately be ignored in computing productivity.
(E) The number of letters delivered is relevant to measuring the productivity of postal workers.
Got your answer? Let’s start going through this one! (Note: if you aren’t yet familiar with the 4-step process for answering CR questions, take a look at this article.)
Step 1: Identify the Question
This question stem is unusual “ it doesn’t actually contain the typical markers that we’d expect to see on a CR problem. That fact makes this question harder and it’s also the key to cracking the question if we want to have a hope of answering it correctly at all, let alone very quickly.
This question stem actually contains a wealth of information! The first few words tell us that there’s some kind of opinion and counter-opinion in the argument (someone is objecting to something) but that counter-opinion is only implied, not stated outright.