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GMAT Critical Reasoning: Find the Conclusion or Inference

To start, here are a couple GMAT Critical Reasoning Practice questions of the “Find the Conclusion/Inference” type.

1) Diamond Enterprises is a store in Apisville that sells specialty luxury items.  For several years, Diamond reaped substantial profits and was considering building branch stores in nearby counties.   Stibium Industries, for several years the single largest employer in Apisville and the surrounding region, abruptly closed its plant last year, causing widespread unemployment.  Only a fraction of the former Stibium workers have found new jobs, and many of these at much lower wages.  Early this year, Diamond Enterprises has filed for Chapter 11 bankruptcy, citing the closure of Stibium as one of the primary causes.

Which of the following inferences is best supported by the passage?

  1. Diamond Enterprises would have avoided bankruptcy if it had followed through with the plan to build branch stores during its more prosperous years.
  2. Stibium’s management team had a corporate account with Diamond Enterprises, and ordered several luxury items used in business meetings and to entertain prospective clients.
  3. Diamond’s direct competitors, in Apisville and in the surrounding region, are much larger than Diamond, and therefore benefitted substantially from the conditions that arose after Stibium closed.
  4. The closure of Stibium resulted in a loss of revenue for Diamond Enterprises.
  5. After Stibium Industry closed, Diamond Enterprises was the single largest employer in Apisville.

2) Public Health Official: After several years of vaccinating all of the citizens of this state for Tacitus’ Disease, a highly infectious virus, state hospitals have cut costs by no longer administering this vaccine, starting at the beginning of this year. A state senator defended the position, arguing that after several years with zero incidence of the disease in the state, its citizens were no longer at risk.  This is a flawed argument.  Our state imports meats and produce from countries with high incidences of diseases for which our country has vaccines.  Three years ago, when we reduced the use of the Salicetiococcus vaccines, a small outbreak of Salicetiococcus among young children, fortunately without fatalities, encouraged us to resume use at the previous vaccines.

The public health official’s statements, if true, best support which of the following as a conclusion?

  1. Young children of the state will be at risk for Tacitus’ Disease.
  2. Some of the meats imported to this state do not have adequate refrigeration during the shipping process.
  3. Tacitus’ Disease is a much deadlier disease than Salicetiococcus, and has a correspondingly higher fatality rate.
  4. No food products produced within the state bear any contaminants that could lead to either Tacitus’ Disease or Salicetiococcus.
  5. The cost of providing all citizens of the state with the Tacitus’ Disease vaccine places an undue burden on the budget of state health agencies.

 

The Conclusion/Inference Question Type

On GMAT Critical Reasoning, the “big three” question types are (1) find the assumption, (2) strengthen the argument, and (3) weaken the argument.  Among the remaining question, this type, the Conclusion/Inference question, is one of the most common.  Prompts for this type include questions such as these:

Which of the following must be true on the basis of the politician’s statements above?
Which of the following conclusions is most strongly supported by the information above?
If the above statements are true, which of the following inferences is best supported by them?
In this question type, the prompt presents statements P & Q & R, and your job is to draw a conclusion or inference that is best supported by these statements.

 

The format of wrong answers

Virtually all the incorrect answer choices of this type follow the same pattern.  In plain language, they go too far.  Virtually all the incorrect answer choices will require some kind of additional assumption, over and above the individual statements made in the prompt.

Here’s a simplistic example.  Consider the following statements as a quasi-prompt.

Two years ago, I lived and worked in San Francisco.  Now I live and work in Berkeley.

As it happens, both of those statements are 100% true in real life.  Here are examples of incorrect inferences

  1. I get paid more at my job in Berkeley. (We don’t know)
  2. I enjoy my job in Berkeley more than my job in San Francisco. (We don’t know)
  3. My commute to work now is about the same distance as it was when I lived and worked in SF. (We don’t know)
  4. I left my job in SF to come to this job in Berkeley. (We don’t know)
  5. These two jobs are in a similar line of work.   (We don’t know)

Some of those happen to be true, and others aren’t true.  The point is, though, none of them is a necessary deduction from the prompt.  For any of them, we could easily imagine a world in which the prompt statements were true and the inference statement was false.  Each one of these requires an additional assumption, beyond what a strict reading of the prompt tells us.  Every single one of these would be a wrong answer on an Inference/Conclusion question on the GMAT Critical Reasoning.

 

A good conclusion or good inference

As with inferences on GMAT Reading Comprehension, a good inference or good conclusion on the GMAT Critical Reasoning is just half a step away from what is stated explicitly.  It is something that, given the information in the prompt, is simply undeniable.

Consider another quasi-prompt, more a story than a legitimate GMAT CR prompt:

As soon as the suspect ran out of the bank, he started shooting at the policemen standing on the corner.  As he ran away, he kept firing back at the policemen.  The policemen took cover and returned fire.  One policemen hit the suspect just as he was about to get into a waiting car.  As the police approached, the car sped away without the suspect, allowing the police to apprehend and arrest the suspect. 

Again, here are incorrect, unsupported conclusions

a. The suspect robbed the bank.  (We don’t know)

b. The suspect was not as good a marksman as were some of the police.  (We don’t know)

c. The suspect already had a criminal record before this incident.  (We don’t know)

d. The suspect was trying to kill the police.  (We don’t know)

e. The police were trying to kill the suspect.  (We don’t know)

f. The suspect’s accomplices, all armed with guns, were in the waiting car.    (We don’t know)

g. If the suspect had not been hit, he would have reached the car, escaped, and eluded arrest.   (We don’t know)

Any of those could be true, but that’s not the point in this question type.  We are looking for something that is undeniable, something that absolutely has to be true, as a result of the information in the prompt.   Here are a couple examples of well-supported conclusions:

h. The police were firing in self-defense.

i. If the suspect had not been hit, he would have fled the scene in the car.

The prompt says that the suspect shot first, and that the police were merely returning fire once fired upon — that is more or less the legal definition of self-defense, which is why (h) is a well-supported conclusion.

The story explicitly says that the suspect was hit “just as he was about to get into a waiting car“, so that strongly suggests that, if he had not been hit, he would have gotten into the car.  As it is, the car apparently left the immediate scene without difficulty, so if the suspect had gotten into the car, he would have fled the scene —- (i) is another good conclusion.  Notice the crucial difference between (g) above and (i).  Whereas (i) makes the conservative assumption that the suspect merely would have fled the scene, i.e. left that particular location, (g) paints a much grander picture about the total escape he would have been able to make with this car.  As soon as that car pulls out of this story, it might be intercepted by police cars.  It might be easily stopped on roads less than a mile from this site and all occupants arrested.  We don’t know.  We don’t know whether that car ultimately would be some kind of ticket to freedom for the suspect.  All we know for sure is, the car actually left the immediate vicinity.  That’s why (i)  is a good conclusion, and (g) is not.

 

Summary

If you had an “aha’s” while reading this, you may want to give the two questions at the top another look before reading the explanations below.   Here’s another question of this genre for practice:

3) http://gmat.magoosh.com/questions/3149

If you have any questions or anything you would like to say, please let us know in the comments section at the bottom.

 

Practice Question Explanations

1) The credited answer is (D).  We know Diamond had high profits before Stibium closed, and we know it was close to bankruptcy after Stibium closed, citing Stibum’s closure as one of the primary causes.   There, in some way, as a result of Stibium closing, Diamond lost revenue.  Consider the opposite of (D): If Stibium closed, and that caused no revenue loss for Diamond, then how on earth could Diamond cite the closure of Stibium as one of the causes of its plummet from high profits to bankruptcy?  The opposite of (D) is a scenario that makes no sense, so (D) is an unavoidable inference, very well supported.

Choice (A) is a tempting answer.  Would branches of other Diamond stores in other towns have reaped profits, enough to avoid the bankruptcy mentioned?  Perhaps.  That’s certainly a plausible possibility, but we don’t know for sure.  If we don’t know for sure, it’s not a good inference.  (A) is incorrect.

Choice (B) is way too specific in the kind of assumptions it makes.  It seems that Diamond was getting some kind of revenue from Stibium, but was it the management buying perks? or rank-and-file workers buying treats for themselves?  We don’t know.  Anything that spins a highly specific story is too much to infer strictly from the information in the prompt.    (B) is incorrect.

Choice (C) makes too many assumptions — does this specialty store Diamond have direct competitors in the region? if so, are these competitors larger?  was “being larger” an advantage in the economic conditions that resulted from Stibium’s closure?  There are too many things we don’t know, so we can draw a clear inference.  (C) is incorrect.

Choice (E) is entirely unfounded.  We have no idea how big Diamond is, and we have no idea what other employers Apisville might have.  (E) is incorrect.

(D) is by far the best answer.

 

2) The credited answer is (A).    We know the citizenry currently is immune because of the vaccine.  If they stop immunizing folks, the unvaccinated ones, i.e. the young children, would be vulnerable to this “highly infectious” diseases.  We don’t know for sure that they will definitely get Tacitus’ Diseases, but we certainly know that their unvaccinated immune systems would be “at risk” for it.  This is a well-supported conclusion.

Choice (B) is tempting.  We know the countries that export meat & produce to this state have many of these diseases.  It is suggested that these imports could constitute a vector for Tacitus’ disease into the state.  We don’t know whether diseases could be introduced through these imports, but even if they are, there’s no reason to conclude meats are unrefrigerated.  Unrefrigerated meat spoils very quickly, which suggest that it never could be sold once it arrived here.  Furthermore, refrigerator doesn’t destroy viruses — they can simply remain dormant until they thaw.  We have no grounds for concluding this.  (B) is incorrect.

Choice (C) is unsubstantiated: we have no way to compare the infection rates.  (C) is incorrect.

Choice (D) might be tempting, but we just don’t know.  The whole population has been immune to Tacitus’ disease for years, because they all have been vaccinated.  We don’t know by what pathways the Tacitus’s disease virus might be entering the population.  We have no reason to assume this.  (D) is incorrect.

Choice (E) is not a solid conclusion.  We know that it cost something for the state hospitals to provide the Tacitus’ disease vaccine.  Was this cost high?  Did it place an economic burden on the state health services?  We don’t know.  We have no grounds for drawing this specific conclusion.  (E) is incorrect.

 

About the Author

Mike McGarry is a Content Developer for Magoosh with over 20 years of teaching experience and a BS in Physics and an MA in Religion, both from Harvard. He enjoys hitting foosballs into orbit, and despite having no obvious cranial deficiency, he insists on rooting for the NY Mets. Follow him on Google+!

12 Responses to GMAT Critical Reasoning: Find the Conclusion or Inference

  1. Umang Mathur September 25, 2014 at 11:14 pm #

    Hi Mike,
    It is a delight to read your blogs, thanks a lot for such nice and descriptive blogs. I am not convinced with the explanation to 2nd question.

    While preparing for CR, I read in one of the books that, the premise of the question should only be the information mentioned in the question. In the second question, we are assuming that the children are prone to Tacitus’ Disease, where as the question premise suggests that Salicetiococcus affected children.

    Aren’t we making this assumption while coming to our conclusion.

    Cheers!!!
    Umang

    • Mike
      Mike September 26, 2014 at 10:19 am #

      Dear Umang,
      I’m happy to respond, my friend. :-) That’s an excellent question.
      This is a funny thing about GMAT CR: on the one hand, you don’t need outside knowledge of the very specific topic discussed in a question (in this case, these diseases are totally made-up, so one couldn’t have knowledge of them!) BUT, students make the mistake of thinking that ALL outside knowledge is irrelevant, and that is a profound misunderstanding. See this blog:
      http://magoosh.com/gmat/2014/gmat-critical-reasoning-and-outside-knowledge/
      In this question, you do have to have a general understanding of disease and of how and why vaccines work. You don’t need to know the biochemical details: you just have to have a vague general understanding. For example, in the modern world, nobody gets polio, precisely because we all receive a vaccine for it. If we stopped giving the vaccine, say, in 2014, then the unvaccinated folks, who would be young children in the next few years, would be the ones at risk. The risk has nothing to do with their age itself, but simply the fact that if we stopped vaccinating at any point, shortly after that, the only unvaccinated people would be the children born since that date.
      That’s precisely what this argument is about. It’s not relying on assumptions about who would be susceptible to this particular fictional disease. Instead, it is relying on an understanding of the general pattern true for all diseases that have vaccines. These general real-world patterns — in science, in history, in business — are very important to understand if you want to be successful on the GMAT CR.
      Does all this make sense?
      Mike :-)

  2. Mritunjay July 3, 2014 at 7:12 pm #

    Dear Mike ,

    Thanks for nice explanation . I understood how to get correct conclusion .

    My query is how to differentiate inference and conclusion for same question and options ?

    Please explain .

    Regards
    Mritunjay.

    • Mike
      Mike July 4, 2014 at 1:16 pm #

      Dear Mritunjay,
      I’m happy to respond. :-) My friend, understand that what you are asking is NOT a skill needed for the GMAT. The GMAT will ask you to find the conclusion of an argument, or to find an inference, but it will NEVER ask you to differentiate between a conclusion for an inference. An inference will never be an incorrect choice on a conclusion question, and vice versa. You don’t need to know this at all.
      Does this make sense?
      Mike :-)

  3. Neha July 25, 2013 at 8:53 am #

    Hi Mike,

    Thank you for the excellent post!

    My doubt is in first question. The correct answer is (D) The closure of Stibium resulted in a loss of revenue. Isn’t this sentence incomplete? It does not specify whose ‘loss of revenue’ – Diamond’s loss of revenue or some other company’s loss of revenue. While I was reading answer choices, I got confused because answer stem does not specify whose ‘loss of revenue’ it is addressing to.

    • Mike
      Mike July 25, 2013 at 12:58 pm #

      Dear Neha,
      I actually changed the question, making it a big more specific, although it’s not clear to me that this was necessary. The prompt concludes by telling us Diamond Enterprises is filing for bankruptcy, so the “loss of revenue” rather clearly refers to Diamond. Beware of approaching the RC & CR too literally. It’s true the GMAT discourages wild leaps of logic, but you will also run into problems if you need everything specified hyper-explicitly. Real-world reading, for example, the Economist magazine, will give you a good sense of this subtle distinction.
      Does this make sense?
      Mike :-)

      • Neha July 30, 2013 at 6:26 am #

        Dear Mike,

        Thanks for your response.

        I just attempted GMAT for the second time. First time, I screwed up and landed in scoring 580. This time, I have a 100 points jump and scored 680. I had just 2 weeks time to prepare and I must say credit goes to your blogs. :)

        I went through all your blogs, especially verbal section and even gone through your e-book. All tricks and points you mentioned, are wonderful, easy to grasp and of course, benefited me the best in scoring higher this time.

        Thank you for the fantastic blogs! I would like to mention that even magoosh course is very good. I would have bought the full course, however, given the short time I had (just 4-5 days), I were not able to finish it. I would recommend the course provided in magoosh, for sure!

        Keep up the good work!!

        • Mike
          Mike July 30, 2013 at 10:01 am #

          Dear Neha,
          Thank you very much for your kind words. Best of luck to you, my friend. May the Force be with you! :-)
          Mike :-)

  4. Sudha June 27, 2013 at 2:27 am #

    Mike
    My Friend, Answer choiceA, does it not undermine public health officials statement, the question is to strengthen the officials argument,

    counter argument in the passage is that, imported meats can be a cause out break.

    what if official staes that if the refrigaration facilities are good then the outbreak would not take place

    are we suppose to infer that thier are no young children left in the state?

    • Mike
      Mike June 27, 2013 at 1:35 pm #

      Dear Sudha,
      I don’t think you understand the question. Our job is NOT to strengthen the public health official’s statements, but rather to identify a statement that the public health official’s statements support. I think you have the direct of support reversed.
      As for why (A) is correct, I suggest reading the respond to vikram below.
      Mike

  5. vikram June 20, 2013 at 6:55 pm #

    Hi Mike,

    I am not sure about the answer to the 2nd question. To me, all the answer choices seem out of scope. So what Salicetiococcus affected children. you can’t conclude that Tacitus’ Disease will also affect children. May be it will affect adults. As you stated “conclusion type” question must be true. Can you please comment on this ?

    Thanks !

    • Mike
      Mike June 21, 2013 at 11:33 am #

      Vikram —
      Most diseases, especially highly infectious ones, affect everyone. In the case of Salicetiococcus, the whole population had been inoculated, which protected them from the disease. When the vaccines were no longer given, a generation of children born after that started to grow up who had not been inoculated — they were the only ones vulnerable to the disease because they were the only ones who hadn’t received the vaccine. —- Everything about that scenario is true for Tacitus’ Disease as well. Again, it’s not that either disease specifically target children (that would be somewhat unusual). Rather, as with most diseases, folks with vaccines are protected and folks with them are not —- if everyone had been vaccinated up to a certain point in time, that means the only folks who haven’t received the vaccine are children.
      Does this make sense?
      Mike :-)


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