GMAT Avengers Study Group: CR Assumptions:

by on October 28th, 2014

Assumption questions on the CR section of the GMAT exam are one of the 4 major CR question types. The four major CR types are Find the Assumption, Strengthen, Weaken, and Inference. The majority of CR questions will be in one of those four categories.

Assumption questions ask us for a piece of support that isn’t explicitly stated but is necessary for the argument to remain valid. When a question asks for what’s missing from the argument or what the argument depends on, then it’s asking us to find the author’s necessary assumption.

Some sample Assumption question stems are as follows:

“The commentator’s argument relies on which of the following assumptions?”
“The official’s conclusion logically depends on which of the following assumptions?”
“Which of the following is an assumption made in drawing the conclusion above?”

Remember that all GMAT arguments contain one or more assumptions; identifying the assumptions is the most important step when answering any CR question based on an argument. An assumption is the unstated evidence necessary to make the argument work. It basically bridges the gap between two pieces of the argument, usually between conclusion and evidence but occasionally between two unconnected pieces of evidence. Without the assumption, the argument falls apart. We can think of it as something the author must believe but doesn’t directly state. The relationship between the various parts of an argument can be visualize as follows:

Evidence + Assumption(s) —> Conclusion

Negation/Denial Test Technique

An assumption must be true in order for the conclusion to follow logically from the evidence. Therefore, in an assumption question, we can test each answer choice by negating it—in other words imagining that the information given in the answer choice is false.

If you negate a statement, and it’s still possible to imagine that the conclusion is still true even with this negated statement, then that original statement is definitely not an assumption of the argument.

If you negate a statement, and this negated statement is a devastating objection which shatters the argument and makes the conclusion untenable, then that original statement is an assumption of the argument.

It is a very powerful technique on CR assumption questions. We should learn common logical negations while doing the Negation Test.

  • Some vs. None
  • All vs. Not all (or Some … not)
  • Could vs. Cannot
  • Must be true vs. not necessarily true

The recommended strategies for tackling the entire CR process is described here.

Takeaways for Find the Assumption questions:

  1. The question stem will usually contain some form of the word assumption. The argument will contain at least one premise, a conclusion, and some unstated assumptions that bridge the gap between the premise(s) and conclusion.
  2. Always brainstorm possible assumptions before going to the answers. In case, this does not work, consider the answers carefully, narrowing down as you go, and be prepared to guess if you get stuck.
  3. If we have narrowed to a couple of tempting answers and are stuck, we can try the Negation technique on Find the Assumption answer choices. Reverse the answer and see how that affects the argument. When the correct answer is negated, the argument should be weakened. When incorrect answers are negated, the argument shouldn’t be affected much (if at all).

Let’s quickly recap the articles that we shared on our Facebook Event Page. Do give the articles linked below a read before trying the practice problems.

Practice Problems

1) About two million years ago, lava dammed up a river in western Asia and caused a small lake to form. The lake existed for about half a million years. Bones of an early human ancestor were recently found in the ancient lake-bottom sediments that lie on top of the layer of lava. Therefore, ancestors of modern humans lived in Western Asia between two million and one-and-a-half million years ago.

Which one of the following is an assumption required by the argument?

(A) There were not other lakes in the immediate area before the lava dammed up the river.

(B) The lake contained fish that the human ancestors could have used for food.

(C) The lava that lay under the lake-bottom sediments did not contain any human fossil remains.

(D) The lake was deep enough that a person could drown in it.

(E) The bones were already in the sediments by the time the lake disappeared.

2) In North America there has been an explosion of public interest in, and enjoyment of, opera over the last three decades. The evidence of this explosion is that of the 70 or so professional opera companies currently active in North America, 45 were founded over the course of the last 30 years.

The reasoning above assumes which one of the following?

(A) All of the 70 professional opera companies are commercially viable options.

(B) There were fewer than 45 professional opera companies that had been active 30 years ago and that ceased operations during the last 30 years.

(C) There has not been a corresponding increase in the number of professional companies devoted to other performing arts.

(D) The size of the average audience at performances by professional opera companies has increased over the past three decades.

(E) The 45 most recently founded opera companies were all established as a result of enthusiasm on the part of a potential audience.

3) The technological conservatism of bicycle manufacturers is a reflection of the kinds of demand they are trying to meet. The only cyclists seriously interested in innovation and willing to pay for it are bicycle racers. Therefore, innovation in bicycle technology is limited by what authorities will accept as standard for purposes of competition in bicycle races.

Which of the following is an assumption made in drawing the conclusion above?

(A) The market for cheap, traditional bicycles cannot expand unless the market for high-performance competition bicycles expands.

(B) High-performance bicycles are likely to be improved more as a result of technological innovations developed in small workshops than as a result of technological innovations developed in major manufacturing concerns.

(C) Bicycle racers do not generate a strong demand for innovations that fall outside what is officially recognized as standard for purposes of competition.

(D) The technological conservatism of bicycle manufacturers results primarily from their desire to manufacture a product that can be sold without being altered to suit different national markets.

(E) The authorities who set standards for high-performance bicycle racing do not keep informed about innovative bicycle design.

4) Diabetes is a disease in which the body does not produce or properly use insulin, a hormone that is needed to convert glucose into energy needed for daily life. Because ice cream commonly contains glucose in the form of sucrose, diabetics generally experience discomfort after consuming even a small serving of ice cream. However, since there are several ice cream companies who add sucrose to none of the ice cream they produce, diabetics are able to eat ice cream without experiencing discomfort due to glucose intolerance afterward.

Which of the following is an assumption on which the argument depends?

(A) These ice cream companies have been able to duplicate the taste of sucrose derived from glucose by means that do not involve adding any potential substances that may be of discomfort to diabetics.

(B) Not all forms of glucose are equally likely to result in this discomfort.

(C) Ice cream is not the only food to which glucose is commonly added.

(D) Apart from glucose, there are no substances commonly present in ice cream that would cause discomfort to diabetics.

(E) Glucose is not naturally present in the ice cream produced by these ice cream companies in amounts large enough to cause discomfort to diabetics who eat this ice cream.

5) Politician: It is important for members of the State Assembly to remember that Governor Norman’s proposed new state thruway was part of her platform during her landslide re-election campaign last year. This means that if the thruway plan is defeated, its opponents will have much to answer for in next November’s State Assembly elections.

The politician’s argument relies upon which of the following assumptions?

(A) Many of those who voted for Governor Norman oppose the thruway proposal.

(B) The thruway proposal is likely to be defeated by the State Assembly.

(C) Many of those who voted for Governor Norman supported the thruway proposal.

(D) Everyone who voted for Governor Norman last year will vote in the State Assembly elections.

(E) Those members of the State Assembly who oppose the thruway proposal do not have valid reasons for opposing it.

6) Every four years, the city council of Townsville drafts a city plan over the course of a series of city renewal meetings. By design, the council spends the majority of its time considering initiatives presented by each council member. These initiatives address the needs of each council member’s individual constituents. The council eventually succeeds in reaching a compromise that effectively balances the needs of Townsville’s diverse factions. But on final analysis, the meetings fail to draft an effective city plan, as the council invariably fails to reach a resolution that will achieve a vision that benefits the greater whole of Townsville.

Which of the following is an assumption upon which the argument depends?

(A) There are too many insignificant factions within Townsville that influence the city council’s plans.

(B) The city council does not devote enough time to building an effective city plan.

(C) The city council should not commit time to considering the needs of the constituents of each individual council member.

(D) Reaching a shared compromise that balances factional interests should be the primary goal of local government.

(E) An effective city plan must achieve a vision that helps the town as a whole.

7) In a study conducted in Canada, servers in various restaurants wrote “Thank you” on randomly selected bills before presenting the bills to their customers. Tips on these bills were an average of three percentage points higher than tips on bills without the message. Therefore, if servers in Canada regularly wrote “Thank you” on restaurant bills, their average income from tips would be significantly higher than it otherwise would have been.

Which of the following is an assumption on which the argument relies?

(A) The “Thank you” messages would have the same impact on regular patrons of a restaurant as they would on occasional patrons of the same restaurant.

(B) Regularly seeing “Thank you” written on their bills would not lead restaurant patrons to revert to their earlier tipping habits.

(C) The written “Thank you” reminds restaurant patrons that tips constitute a significant part of the income of many food servers.

(D) The rate at which people tip food servers in Canada does not vary with how expensive a restaurant is.

(E) Virtually all patrons of the Canadian restaurants in the study who were given a bill with “Thank you” written on it left a larger tip than they otherwise would have.

8) The Earth’s rivers constantly carry dissolved salts into its oceans. Clearly, therefore, by taking the resulting increase in salt levels in the oceans over the past hundred years and then determining how many centuries of such increases it would have taken the oceans to reach current salt levels from a hypothetical initial salt-free state, the maximum age of the Earth’s oceans can be accurately estimated.

Which of the following is an assumption on which the argument depends?

(A) The quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years.

(B) At any given time, all the Earth’s rivers have about the same salt levels.

(C) There are salts that leach into the Earth’s oceans directly from the ocean floor.

(D) There is no method superior to that based on salt levels for estimating the maximum age of the Earth’s oceans.

(E) None of the salts carried into the Earth’s oceans by rivers are used up by biological activity in the oceans.

9) For several years, Nighttime News attracted fewer viewers than World News, which broadcasts its show at the same time as Nighttime News. Recently,the producers of Nighttime News added personal interest stories and increased coverage of sports and weather. The two programs now have a roughly equal number of viewers. Clearly, the recent programming changes persuaded viewers to switch from World News to Nighttime News.

Which of the following is an assumption on which the author relies?

(A) Viewers are more interested in sports and weather than in personal interest stories.

(B) The programming content of Nighttime News is more closely aligned with the interests of the overall audience than is the content of World News.

(C) Some World News viewers liked the new Nighttime News programming better than they liked the World News programming.

(D) There are other possible causes for an increase in the number of viewers of Nighttime News, including a recent ad campaign that aired on many local affiliates.

(E) The quality of World News will remain constant even if Nighttime News improves.

10) Following a review of the findings of a recent study by the Ministry of Education, the ministry’s conclusion is that children who do not have television sets in their bedrooms are more likely to have greater success in college programs later on than children who do. The study determined that children who have television sets in their bedrooms achieve, on average, school grades much lower than those without television sets in their bedrooms. In response to the report, some parents claimed that it was not the fact that their children had television sets in their rooms that affected their grades, but that the programs that were shown contained little or no educational value.

The above conclusion is properly drawn if which of the following is assumed?

(A) Parents often feel the need to defend the choices they make in regards to the raising of their children.

(B) When children have television sets in their bedrooms, parents find it difficult to supervise the amount of viewing children may partake in.

(C) The success of a student in a college program depends on that student’s determination.

(D) The skills needed to achieve good grades at school and at college are the same, and the effects of having a television in the bedroom are prolonged.

(E) The Ministry of Education is interested in educating parents about the effects of providing children with television sets in their bedrooms.

11) Nutritionist: Multivitamins are potent storehouses of antioxidants, substances that fight the oxidation process, which breaks down the body. Nonetheless, according to longitudinal studies—studies that follow subjects over the course of many years—those who take multivitamins every day have a decreased longevity. Clearly, if people want to live longer they should avoid antioxidants.

Which of the following is an assumption the argument relies on?

(A) The use of antioxidants does not vary across different age groups.

(B) The less often one takes multivitamins, the more one’s longevity increases.

(C) The antioxidants found in vitamins do not differ from antioxidants found in other sources, such as food.

(D) Antioxidants can confer health benefits that do not relate to longevity.

(E) Antioxidants destroy free radicals, which are toxic to the body.

12) In recent years, a village outside Osaka, Japan has taken to hosting a ninja festival, a celebration of Japan’s heritage that reflects on its feudal past while exalting its pop culture driven present. But clearly only children take this festival seriously, for they are the only attendees who bother to dress up as ninjas.

Which of the following is an assumption on which the argument depends?

(A) Any attendee who dresses up as a ninja takes the festival seriously.

(B) No attendee who takes the festival seriously would fail to dress up as a ninja.

(C) Anyone who is not dressed up as a ninja is not attending the festival.

(D) The festival organizers have instituted a ninja-themed dress code.

(E) If an attendee is not dressed as a ninja, then that attendee will not be taken seriously by other attendees.

13) Consumer Advocate: The new soft drink, Mango Paradise, contains at least 2.5% of Ephedra, a chemical supplement that stimulates the activity of the nervous system but may also result in serious cardiac problems. Therefore, this drink is harmful to consumer health and should be banned from distribution in our state.

Which of the following is an assumption made by the consumer advocate?

(A) The new soft drink will soon be introduced into mass production.

(B) Consumers are unlikely to enjoy the taste of Mango Paradise because of the high amount of Ephedra contained in the drink.

(C)  Any drink that contains at least 2.5% of Ephedra is harmful to consumer health.

(D) The Consumer Advocate is not affiliated with the producer of Mango Paradise.

(E) Most consumers who drink Mango Paradise will eventually experience serious cardiac problems

14) Frobisher, a sixteenth-century English explorer, had soil samples from Canada’s Kodlunarn Island examined for gold content. Because high gold content was reported,Elizabeth I funded two mining expeditions. Neither expedition found any gold there.

Modern analysis of the island’s soil indicates a very low gold content. Thus the methods used to determine the gold content of Frobisher’s samples must have been inaccurate.

Which of the following is an assumption on which the argument depends?

(A) The gold content of the soil on Kodlunarn Island is much lower today than it was in the sixteenth century.

(B) The two mining expeditions funded by Elizabeth I did not mine the same part of Kodlunarn Island.

(C) The methods used to assess gold content of the soil samples provided by Frobisher were different from those generally used in the sixteenth century.

(D) Frobisher did not have soil samples from any other Canadian island examined for gold content.

(E) Gold was not added to the soil samples collected by Frobisher before the samples were examined.

Answer Key:

  1. E
  2. B
  3. C
  4. E
  5. C
  6. E
  7. B
  8. A
  9. C
  10. D
  11. C
  12. B
  13. C
  14. E

Make sure you check out the event Facebook page to see all the comments that were being exchanged during the live session.

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