GMAT Critical Reasoning

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```					The MBA Center
Critical Reasoning

Part One

Hi, my name is Jeff. I’ll be your instructor for today’s lesson, Critical Reasoning. The speed of this lesson is up to you. Click on the yellow action buttons at the bottom of each screen to move forward or backward Beginning of section

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Aim
Part Two

Logic, not Grammar
Critical Reasoning problems are among the trickiest question types you’ll come across in the GMAT. That’s because CR problems are logic-based. While an understanding of English grammar rules is essential, your major challenge will be simply to learn how ETS expects you to approach the information within the sentences.

For many, this is the most feared part of the test!

Why do they fear it so? Because the world as we know it is not logical.

For Critical Reasoning questions, you must be purely and consistently logical. With each CR question, you’ll be presented with an argument. Don’t try to break down the argument into its essential parts. Instead, reorder the information. Reorder the information; identifying the premises and conclusion inherent within each argument.

By deconstructing a Critical Reasoning argument, you can more clearly see what it is that’s missing.

Deconstructing an argument helps you notice illogical connections. The tendency to make sense of what we read is natural and, for the GMAT, fatal.
Fight your normal reading habits as you go through the questions in this lesson.

We pose arguments all the time.
Often there is no logical connection between the information we present (our premises) and our conclusions.

Don’t assume information unless you see it in the argument!

For example…

You: Me:

Let’s go see a movie. I have only two dollars.

What is your conclusion? But why?

We can’t go to a movie.

Because a movie costs more than two dollars.

But how do we know this?

We don’t!

Make sure you’re not brining outside information into your reading of a Critical Reasoning problem.

Here’s another example…

Me: You: Me:

I can’t believe I saw Joe drinking a Coke. Why? Because Joe works for Pepsi.

What’s your conclusion? Joe prefers Coca Cola. Joe hates his job. Joe is a spy for Pepsi.

Be careful! What kinds of assumptions are you making to reach these conclusions?

What do you make of this one?

On Thursday I wore a blue shirt. On Friday I had a headache. Therefore, my blue shirt gives me a headache.

This is a dumbed-down version of a Critical Reasoning problem. It’s easy to argue with my logic when I present my argument so simply. Be always suspicious of CR arguments. Fight with them. What could you say that would undermine my argument? Perhaps I was out all night last Thursday. Maybe I live next door to an airport.

Any of these statements could severely undermine, or weaken, my argument. And what could you add that would completely destroy it?

There’s no connection between the headache and the shirt This piece of information would completely destroy my argument. And the reverse, that there is a direct connection between the headache and the shirt, would completely fix it. Now take a look at my revised argument…

On Thursday I wore a blue shirt. On Friday I had a headache. My health is affected by the clothes I wear. Therefore, my blue shirt gives me a headache.

You’ll never find an argument like this in a Critical Reasoning problem. It’s too logical!

Critical Reasoning questions ask you to do several things, but central to them all is having an understanding of the basic structure of an argument. Your task as you approach CR questions will be to break down an illogical argument into its stated premises and conclusion. If you can do this, you’ll be able to spot any trick that ETS test-makers throw at you.

There are several different types of Critical Reasoning questions. Differentiating between them is difficult, and you’ll have to know the approach for each of them when you sit down to take the test. Our MBA Center guidebook covers the many CR question types thoroughly. In the next section, we’ll look briefly at these different kinds of CR questions and give you an idea of how it all works.

Key Terms
Argument
Central to every CR question is the argument. An argument is an ordered line of reasoning composed of premises, assumptions, and a conclusion. Understanding the elements of an argument is essential to performing well in this section. Premise Each CR argument contains at least one premise. Premises are pieces of information that provide evidence used to support the conclusion of the argument. For the purposes of Critical Reasoning arguments, premises are facts not subject to dispute. Conclusion The conclusion is the endpoint of the line of reasoning of an argument. Think of it as the result of the argument. The line of reasoning leading to a conclusion is often where errors in logic are made.

Key Terms
Assumption Assumptions are unstated facts and logical connections in an argument. In order for the conclusion of an argument to be true, the assumptions upon which that argument is based must also be true.

The MBA Center Approach
Part Three

The MBA Center Approach
Critical Reasoning questions test your ability to use basic logic to analyze and critique arguments made up of premises and conclusions. ETS test-makers write arguments that assume information which doesn’t exist! A logical and consistent approach is the best way to avoid formulaic traps. Follow these steps each time you attack Critical Reasoning questions. Step 1: Step 2: Step 3: Step 4: Step 5: Read the question first. Read the argument. Paraphrase the argument using your own words. Predict the answer. Use the process of Error Identification to eliminate the wrong answers.

Step 1: Read the question first. It’s natural to read the question after the argument because that’s how they’re presented on the page. This is done for a reason. Reading the argument first is confusing. Read the question and determine what to look for within the answer choices. In general, you’ll be looking for the answer choices that either strengthen or weaken the argument. Think of answer choices as additional premises. Adding any one answer choice to the argument will do one of three things: 1. 2. 2. 3. It will weaken the argument. It will strengthen the argument. It will not affect the argument at all (neutral). It has nothing to do with the argument (out of scope).

Determine which of the eight kinds of Critical Reasoning questions you’re facing before turning to the argument itself.

Step 2: Read the argument. 1. Identify each premise (each piece of information) that is being presented within the argument. 2. Identify the argument’s conclusion. 3. Determine what assumptions are being made.

Step 3: Paraphrase the argument using your own words. Critical Reasoning arguments are intentionally heavy, wordy and complex. Paraphrasing is a good way of understanding the sense an argument presented. Take the time, if necessary, and restate an argument, using words and situations that you can relate to. Note: This is the only step you’re permitted to skip. While it’s necessary to understand the meaning of each argument (and paraphrasing is a good tool to help you do this), restating or paraphrasing an argument brings you unavoidably further away from the actual text.

Step 4: Predict the answer. So, you’ve read the argument. You understand it. You can identify it’s premises and it’s conclusion. Now imagine additional premises (additional pieces of information) and what affect each would have on the argument overall. Brainstorm for a moment. Imagine which additional premise would best strengthen the argument. What one thing could you add that would completely fix it? Now imagine the opposite. How could you weaken the argument? How could you completely destroy it? This is perhaps the most important step in the process. Answer choices are intentionally misleading, and you can use your predictions as a measuring stick with which to compare the choices given to you by ETS.

Step 5: Use the Process of Error Identification to eliminate the wrong answers.

Think of answer choices as additional premises. As you read each choice, ask yourself, “How would this additional premise affect the strength or weakness of the argument’s conclusion?”
Categorize answer choices as one of the following: 1. 2. 2. 3. Strengthen Weaken Neutral Out of scope

Use the Process of Error Identification to get rid of any choices that do not affect the conclusion (neutral) or have nothing to do with the argument whatsoever (out of scope). Whether you eliminate strengthen or weaken answer choices depends on the question related with that argument. Try the following Critical Reasoning example, using the MBA Center’s five steps…

In years past, professional baseball players lifted weights less but were also injured less often during games. Obviously, the more an athlete lifts weights, the higher the likelihood of injury. The conclusion above presupposes which of the following? (A) The increase in baseball injuries is due to a factor other than weightlifting. (B) The activities of baseball players represent those of athletes as a group. (C) Most baseball injuries today result from too much weightlifting. (D) There is no proven correlation between how much athletes lift weights and how likely they are to be affected by injury. (E) Weightlifting has always been common practice for professional athletes.

The correct answer is (B). Let’s see how it’s done…
First, read the question. The conclusion above presupposes which of the following?

This is what’s called an assumption question. What specific piece of information is presupposed (assumed) in the preceding argument?
Break it down to understand what the writer is really saying. Can you identify the premises and the conclusion?

Premise #1: In years past, professional baseball players lifted weights less. Premise #2: But they were also injured less often during games. Conclusion: Obviously, the more an athlete lifts weights, the higher the likelihood of injury.
Restate or paraphrase the argument, if necessary. Stick as close to the actual text as possible.

If necessary, paraphrase the argument. Put the events in a context you can understand, but stick as close to the actual text as possible. Try changing the subjects without changing what they did.
Keep trying until the GMAT argument makes sense to you. return to the actual argument! Then

Now, think about some of the big assumptions that are being made.
Ask yourself what you could add to fix the argument. What could you add to the argument to completely destroy it! If it helps, imagine someone you can’t stand. Think up a real or fictional know-it-all. Now come up with the one thing you could say to this person that would shut him up. What if I offered evidence that proved baseball injuries are definitely not a result of weightlifting? That might destroy the argument. And the contrary, that baseball injuries definitely are a result of weightlifting, might fix it.

What other assumptions can you come up with?

Use the Process of Error Identification to eliminate any answer choices that are neutral or out of scope. For this particular question, also eliminate any answer choices that weaken the argument.

(A) The increase in baseball injuries is due to a factor other than weightlifting. (B) The activities of baseball players represent those of athletes as a group. (C) Most baseball injuries today result from too much weightlifting. (D) There is no proven correlation between how much athletes lift weights and how likely they are to be affected by injury. (E) Weightlifting has always been common practice for professional athletes.

Only answer choices (B) and (C) strengthen the argument.
Of course, there are many different kinds of athletes. All athletes are not baseball players. The correct answer is (B). Be aware of vague and undefined categories, such as “athletes.” Weakens (A) The increase in baseball injuries is due to a factor other than weightlifting. (B) The activities of baseball players represent those of athletes as a group. (C) Most baseball injuries today result from too much weightlifting. (D) There is no proven correlation between how much athletes lift weights and how likely they are to be affected by injury. (E) Weightlifting has always been common practice for professional athletes. What’s wrong with answer choice (C) ? The trigger word “most” is undefined. “Most” is a relative term, but we don’t know what it’s relative to.

Weakens

Neutral

Try one more… In 1991, produce growers began using a new, inexpensive pesticide, provoking many objections that they would damage both the environment and the produce they were growing. However, the fears have proven unfounded as, though 1996, produce prices had dropped and no ill effects had been reported.
Which of the following, if true, would be the strongest objection to the argument above? (A) Consumption of the produce declined from 1991 to 1993, but rose sharply from 1994 to 1996. (B) Several areas in which use of the pesticide was forbidden have also experienced a drop in produce prices. (C) The amount of produce grown in 1991 was larger than that of 1996. (D) The time since the beginning of the use of the pesticide has been too short to allow some of the predicted effects to occur. (E) Since 1992, new pesticides have been developed that scientists agree are relatively risk-free.

(D) is the only answer choice that weakens the argument.
All the others, in fact, are out of scope! Make it personal… Sorry, the correct answer is (D).

In 1991, I started smoking cigarettes. My friends said it is unhealthy. In 2000, I am still Okay: Therefore; cigarettes are not unhealthy.

There’s a fatal flaw to this logic. Look back and compare this rephrasing with the actual argument itself.

(D) is the only answer choice that weakens the argument.
All the others, in fact, are out of scope! Make it personal…

Good job!

In 1991, I started smoking cigarettes. My friends said it is unhealthy. In 2000, I am still Okay: Therefore; cigarettes are not unhealthy.

There’s a fatal flaw to this logic. Look back and compare this rephrasing with the actual argument itself.

Practice, Practice, Practice!
The best way to prepare for Critical Reasoning questions is to practice Critical Reasoning questions. Take your time as you go through the test questions in the next section. Follow the MBA Center steps. If have difficulties, don’t worry. Critical Reasoning is the most dreaded question type in the exam! Look through the MBA textbook for a full explanation of all the eight types of CR questions.

Good luck!

Critical Reasoning Question Types
The GMAT is, if anything, predictable. There is a limited variety of questions you’ll be asked relating to a Critical Reasoning argument. There are, in fact, eight definitive types of Critical Reasoning questions. Each question type has its own traps and a specific strategy is required to ace each one of them.

The MBA Center textbook offers a thorough explanation of the specific strategies and the differences between each of the eight types of CR questions. In this on-line lesson, we discuss the most common types (strengthen and weaken the argument), as well as generalities that can be applied to all question types. Click on the Next Screen button to see a brief description of these eight Critical Reasoning question types.

Critical Reasoning Question Types
1. Draw a conclusion 2. Assumption 3. Strengthen 4. Weaken

5. Inference
6. Explain the (apparent) contradiction 7. Complete the passage 8. “Except” questions

Consult the MBA Center GMAT textbook for a full description, with examples, of each of the CR question types

Fire!
Part Four

Weigh each choice carefully before eliminating it.

A scientist planted two groups of plants under identical conditions of light, temperature, humidity, and moisture. Every day he would play sound effects of thunderstorms to one of the groups of plants and sounds of city traffic for the other. The group to which he played thunderstorms all died within a few weeks, but the other group thrived during the experiment. He therefore concluded that the sound of city traffic is more effective for helping plants grow than is the sound of thunderstorms. Which of the following, if true, would most seriously weaken the scientist’s conclusion? (A) The scientist put different varieties of plants in each group. (B) The light affecting the plants changed according to the time of day. (C) The plants in the group for which he played city traffic sounds died several weeks after the experiment. (D) The plants were all purchased at the same time. (E) The plants in the group for which he played city traffic sounds required more water than the scientist actually gave them. Click on the oval that corresponds with your choice.

You’ve got it! We know we have two groups of plants. What’s assumed is that both groups are the same!
Try a harder one…

In response to years of increasing congestion at airport X, the government decided to redistribute landing slots. Henceforth, all international flights arriving from continent A would be rerouted to nearby airport Y, all flights arriving from continent B would continue to land at airport X. Several airlines opposed this measure on the grounds that it would result in lost business. Which of the following, if true, justifies the airline’s conclusion?

(A) The airlines’ customers prefer less congested airports. (B) It takes five minutes more flying time to reach the second airport. (C) There are fewer runways, and thus less capacity, at airport Y. (D) Airport Y is located in a region with better transport links to
the

final destinations of many travelers from continent B. (E) Many customers traveling between continent A and continent B choose certain airlines because of the easy flight connections they offer at airport X.

Sorry, the correct answer is (A). Let’s look at this problem using the MBA Center’s five steps.
Who said the plants in both groups are the same? Step 1: Step 2: Step 3: Read the question first. Read the argument. Paraphrase the argument using your own words.

Step 4: Step 5:

Predict the answer. Use the process of Error Identification to eliminate the wrong answers.
Imagine a piece of new information that would destroy the argument.

Which answer choice will best weaken the argument’s conclusion?

Eliminate any answer choices that strengthen or are out of scope.
If necessary, translate it into something that makes sense. Make it personal. Identify the premises, the conclusion, and the flaw (the assumption).

Here’s an easier one…
A city’s public transportation board has decided to cut costs by reducing the frequency of its bus service from an average of eight minutes to an average of ten minutes between buses. The board announced that it can do so without seriously reducing the quality of service.

Which of the following statements, if true, would most strengthen the validity of the board’s announcement?
(A) The less frequent use of the buses will lower maintenance costs, resulting in savings that can be used for much-needed repairs of the city’s pedestrian bridges. (B) At rush hour, congestion in the city slows bus service by thirty percent. (C) Because of a robust economy in the city, passenger patronage has increased substantially in recent years. (D) The public transportation board has recently gathered data on the levels of ridership on all bus lines, showing that some lines are used by many more riders than others. (E) The contract with the bus drivers union stipulates that the city not lay off any drivers because of reduced bus service.

Right again!
This one’s harder still…

Kobayashi coffee has more caffeine than Marlowe Select coffee. But since Chula Vista coffee has more caffeine than Valentino coffee, it follows that Kobayashi coffee has more caffeine than Valentino coffee. Any of the following, if introduced into the argument as an additional premise, makes the argument above logically correct EXCEPT? (A) Marlowe Street coffee has more caffeine than Valentino coffee. (B) Marlowe Street corree has more caffeine than Chula Vista coffee. (C) Marlowe Street and Chula Vista coffees have the same amount of caffeine. (D) Kobayashi and Chula Vista coffees have the same amount of caffeine. (E) Chula Vista coffee has more caffeine than Kobayashi coffee.

Sorry, the correct answer is (E). Let’s look at this problem using the MBA Center’s five steps.
Step 1: Step 2: Step 3: Read the question first. Read the argument. Paraphrase the argument using your own words.

Step 4: Step 5:

Predict the answer. Use the process of Error Identification to eliminate the wrong answers.
Imagine a piece of new information that would destroy the argument.

Which answer choice will best weaken the argument’s conclusion?

Eliminate any answer choices that strengthen or are out of scope. If necessary, translate it into something that makes sense. Make it personal. Identify the premises, the conclusion, and the flaw (the assumption).

There you go!

It has often been hypothesized that global oil consumption, which increases every year, will deplete the supply of oil, with catastrophic results for the global economy. However, these claims never stand up to scrutiny, as the volume of oil in reserves around the world has remained constant.
Which one of the following, if true, best resolves the apparent paradox? (A) The actual annual consumption of oil is below that which many experts estimate. (B) The cost of operating oil refineries has steadily decreased over time. (C) The consumption of oil has greatly increased in the past 50 years. (D) It is the policy of all major oil producers to locate new reserves at a rate consistent with that at which old reserves are depleted. (E) The number of oil-producing countries has been steadily declining.

Sorry, the correct answer is (A).

Use the Process of Error Identification to eliminate answer choices (B), (C) and (E). Those weaken the argument. Answer choice (D) is neutral. Some lines are used by many more riders than others. This tells us nothing.

Click on the Previous Section button and try these questions again. Our textbook offers a thorough explanation of the different types of Critical Reasoning questions.

Here’s an easier one…
A popular Internet service provider changed its billing system, charging customers per each connection to the system rather than per total hours connected. According to company representatives, under the new system, customers will spend more time connected to the Internet while being billed the same or smaller amounts. Which one of the following statements, if true, would most strengthen the conclusion of the company representatives? (A) Customers will connect to the service less frequently and spend more time connected to the service each time they do. (B) The change in the billing system will attract new customers resulting in increased profits for the company. (C) By spending more time connected to the Internet customers will be able to take advantage of services that previously would have been too expensive. (D) The popularity of other Internet service providers relies on their having billing systems similar to the one this company is adopting. (E) The company’s employees, all of whom have free unlimited Internet access, support the change in billing.

Right again! Wow, you’re a Critical Reasoning wiz. You ought to go on television. This one’s even more difficult…

The owners of gambling casinos are keen to attract inexperienced poker players because, on average, these people lose money to the casino, which increases the casino’s profits. This is because the average inexperienced player does not have sufficient skill at the game to win. Which one of the following can be inferred from the above argument?

(A) There is always an element of chance when playing poker. (B) The probability of winning a game of poker increases with experience. (C) Casinos make extremely large profits. (D) Inexperienced players lose more money than they expect to when playing poker at casinos. (E) All games played at casinos involve an element of risk.

Way to go! Try one more…

Which of the following best completes the passage? Critics of Country A’s trade policy with Country Z contend that Country A’s low tariffs are responsible for its large trade deficit with Country Z. Government officials, however, argue that there is a trade deficit with Country Z because low labor costs in Country Z allow its companies to manufacture goods cheaply. The officials also claim that economic competition from Country Z is responsible for better prices for Country A’s consumers. Therefore, they say, the most logical way to lower the trade deficit without hurting Country A’s consumers is to _________. (A) (B) (C) (D) raise the tariffs on goods imported from Country Z encourage businesses in Country A to reduce their labor costs increase taxes on all goods not manufactured in Country A improve the products manufactured by Country A’s companies and market them heavily in Country A (E) subsidize all of Country A’s companies that manage to maintain their prices at the level of the goods produced by Country Z

Critical Reasoning
Got you that time! You did well, and you only had problems with the final difficult problem. Make sure you go through the Critical Reasoning section in our book.

Critical Reasoning
Good job! You got the second wrong, but the other two were right.

Now you’re ready to go through the practice problems in out book.

Critical Reasoning
Inference is once logical step away from the conclusion. Be careful! This one is an Inference question. The best answer will paraphrase words and ideas from the text and contain an inference just one step in logic away from the message of the text. What’s inferred in the argument… that a player must have skill to win!

(B) is the best answer. I got you on that one. Well done, though. These and other Critical Reasoning questions are discussed in detail in our book.

Critical Reasoning
Good job! You got the first one wrong, but you pulled it back up with two and three. Make sure to go through the Critical Reasoning lesson in our book.

Critical Reasoning
Sorry. You got the second problem right, but the other two were wrong.

Make sure you go through the Critical Reasoning section in our book.

Critical Reasoning
What can I say?

You’re a Critical Reasoning genius!

Critical Reasoning
Sorry. You got the first question right, but you answered the next two wrong.

Critical Reasoning questions are discussed more thoroughly in our textbook.
Make sure you understand these questions before you head into the testing room.

Critical Reasoning
Got you that time! Well done, though. You got four out of five right. Keep it up and you’ll be on your way to Harvard!

Summary
Part Five

Summary
Remember the five steps when approaching CR problems.

You can go through this lesson again. Access the Critical Reasoning lesson through our web site as you did before.