Overview: Strengthen & Weaken | Verbal for GMAT PDF Download

Introduction

Both strengthen and weaken questions ask you to find a new piece of information that if added to the existing argument will make the conclusion either: more likely to be true (strengthen) or less likely to be true (weaken).

Strengthen Questions

Example: 

• Which of the following, if true, most strengthens the argument?
• Which of the following, if true, most strongly supports the author’s claim?

How to Approach

• Let us consider the following question to understand the kind of approach we have to apply while solving strengthening and weakening questions.

Excavations in the summer of 2008 at the sites of Vogelherd caves revealed nearly a complete paleolithic ivory bone flute. This flute is by far the most complete of all of the musical instruments thus far recovered from the caves of Swabia. These finds demonstrate the presence of a well-established musical tradition at the time when modern humans colonized Europe, more than 35,000 calendar years ago.Because the discovered ivory bone flute has 5 holes in it, enough to play 5 notes from the 7-note diatonic scale, musicologists believe that the diatonic musical scale was developed and used thousands of years before it became popular during the Renaissance period in Western Europe.

Which of the following, if true, most strongly supports the hypothesis?

(A) Bone flutes were probably the only musical instrument made by Swabian cavemen.
(B) The mammoth tusk bone used to make the Swabian flute would have been long enough to make a flute capable of playing a complete diatonic scale.
(C) No musical instrument that is known to have used a diatonic scale is of an earlier date than the flute found in the Swabian cave.
(D) Flutes are the simplest wind instrument that can be constructed to allow playing a diatonic scale.
(E) The flute was made from a mammoth bone and the site at which the flute fragment was excavated was in a cave that also contained skeletal remains of wooly mammoths.

Now, upon reading the passage, many may find it confusing as it alternates between discussing the flute and a "well-established musical tradition," touching on the flute's holes and something about a musical scale. To navigate this, the recommended GMAT Pill 3-step Approach can be employed: 1) Identify the conclusion, 2) Visualize the question, and 3) Pre-think the answer. Following these steps, you can efficiently handle such problems in real time with practice.

Step 1: Identify the Conclusion

Typically found at the passage's end, the conclusion follows a structure like "Because X, so Y." Here, X supports Y. In this case, X is the flute having 5 holes, and Y is the diatonic musical scale developed many years ago.

Step 2: Visualize the Question

This is an observation -> conclusion scenario. Visually, it connects the conclusion closely with the support, indicated by the sentence structure ("because X, therefore Y").

Step 3: Pre-think the Answer

The connection is established between "flute holes" and the "musical scale" through the passage. The link is that "holes" correspond to "notes," providing a connection between the flute and the musical scale.

Now, let's consider the answer choices of the given example:

(A) Not relevant. Talks about the flutes being the only instruments made but doesn't establish a connection between a 5-hole flute and a complete musical scale.
(B) Yes. Suggests the flute could originally have had 7 holes, making the connection between "flute holes" and a "complete diatonic scale" stronger.
(C) Not relevant. Discusses the absence of earlier flutes with a diatonic scale but doesn't connect a 5-hole flute specifically to a musical scale.
(D) Not relevant. Mentions the ease of making a scale with a flute but doesn't show how a 5-hole flute is associated with a musical scale.
(E) Not relevant. States the flute was made from mammoth bone, but the bone's origin isn't linked to the musical scale.

Hence, option B is correct.

By pre-thinking and expecting an answer choice that strengthens the connection between "flute holes" and the "musical scale," it becomes clear that choices A, C, D, and E are not relevant. 
This approach helps save time by quickly recognizing irrelevant answer choices without reading them thoroughly, contributing to more efficient problem-solving during the GMAT.

Weaken Questions

• Begin by examining the question stem to understand it's a weaken question.
• Analyze the stimulus to identify the conclusion and how it's supported by the premises.
• Scrutinize the reasoning for any gaps, flaws, or shifts in the subject between the premises and conclusion.
• Look for answer choices that specifically target the identified weaknesses in the stimulus.
• If the stimulus lacks apparent weaknesses, seek an option introducing new information that allows the premises to be true while casting doubt on the conclusion.
• Ensure that, while assessing options, their scope aligns with the premises and the qualifications of the conclusion. For instance, if the conclusion concerns animal suffocation, options discussing poisoning should be considered irrelevant.

Now to understand the weakening concept, we will look into an example:

Increasingly, American businesses requiring customer service phone lines have been utilizing overseas companies that can provide these services at extremely reduced rates. Toll-free calls are routed to countries like India, where low-paid workers have been trained to deal with most of the typical problems consumers have with their credit cards, online services, and computer equipment. Since the companies using these overseas call centers are saving so much money, they will undoubtedly show higher profits than companies that do not.

Which of the following, if true, most seriously weakens the argument?

(A) There is strong competition among overseas call centers to provide the most comprehensive services at the lowest rates.
(B) Consumers opposed to exporting American jobs are willing to pay more for goods and services from companies that don't engage in this practice.
(C) Certain banking services cannot be outsourced, since this would require the release of customer financial data.
(D) Because offshore telephone customer service companies provide only these services, they can train their employees more thoroughly than American companies could.
(E) Some American companies send their own employees overseas to train the call center personnel in their particular business.

Solution:

When dealing with weaken questions, like the one presented here, begin by following the steps employed for assumption questions. Initially, identify the author's conclusion, which, in this case, asserts that companies relocating their call centers abroad will yield higher profits than those that do not.

Subsequently, pinpoint the supporting evidence for the conclusion. 
In this argument, the term "since" serves as the evidence, indicating that companies achieve cost savings by outsourcing their call centers.

Next, seek the assumption, the implicit connection between the conclusion and evidence. 
In this scenario, the assumption lies in the belief that moving a call center overseas does not adversely affect gross revenues.

Lastly, since this is a weaken question, the objective is to find an answer choice that challenges the assumption. 

In this instance, option (B) accomplishes this by suggesting that companies utilizing American labor may command higher prices for their products. Consequently, the cost savings from moving call centers overseas might not necessarily lead to higher profitability compared to retaining call centers in the United States and increasing product prices.

Skills to Solve Strengthening and Weakening Questions

Once you've become skilled at pinpointing the main assumption in a critical reasoning problem, the next crucial skill is figuring out how to make an argument stronger or weaker. Strengthen and weaken questions are more common on the GMAT than assumption questions, so being adept at identifying ways to strengthen or weaken an argument is vital for getting most critical reasoning questions right.

• To strengthen an argument, look for the answer choice that confirms the central assumption is correct. This can happen in two ways. 
• First, the correct answer might basically restate the assumption. If an answer choice would be right for an assumption question, it's likely correct for a strengthen question too. 
• Second, the correct answer can support the assumption by referring to a study, survey, or relevant evidence that makes the assumption more probable. Remember, you just need to make the argument more likely to be right, not certain.
• Weakening an argument follows a similar process but in reverse. Again, there are two possibilities.
  First, an answer that weakens the argument can directly challenge the assumption. Any choice saying the assumption is wrong weakens the argument.
  Second, just as new evidence can strengthen the argument, new evidence can weaken it. Any new info in an answer choice that makes the assumption less probable weakens the entire argument.

Solved Examples

Understanding these common types of strengtheners and weakeners helps you quickly spot correct answers in strengthen/weaken questions, boosting your chances of achieving a higher GMAT score.

Example 1. In an effort to eliminate congestion in the stadium entryways immediately before matches start, Plymouth Soccer Club has announced that it will host children’s soccer exhibitions two hours before matches start, typically at noon. This way, some fans will have an incentive to enter the stadium well before kickoff, keeping the entryways clearer immediately before a match starts. 
Which of the following indicates a reason that the plan may fail to reach its objective?

a. The children’s exhibitions will likely tear up the turf before the premier match begins, resulting in a lower-quality playing surface for the main event.
b. Some fans of the Plymouth Soccer Club must travel for several hours to attend matches at the stadium.
c. The train line taken by most Plymouth Soccer Club spectators to the stadium arrives every four hours starting at 11:30am.
d. The neighboring Canton Soccer Club has found that the best way to incent spectators to arrive early is to discount all concessions up to an hour before kickoff.  
e. Because of its original design, the stadium used by Plymouth Soccer Club has fewer entryways than any other stadium in the surrounding area.
Ans: The train line taken by most Plymouth Soccer Club spectators to the stadium arrives every four hours starting at 11:30am.

Sol: 

• In these “Weaken the Plan” questions, your job is to find a reason that the plan will not work. And "The train line taken by most Plymouth Soccer Club spectators to the stadium arrives every four hours starting at 11:30am" supplies one – if most people cannot arrive before 11:30am, they won’t be able to respond to the new promotion of events before a noon game. 
• Choice "The neighboring Canton Soccer Club has found that the best way to incent spectators to arrive early is to discount all concessions up to an hour before kickoff."is incorrect in that the potential existence of a better plan doesn’t necessarily mean that this plan will not work. 
• Choice "The children’s exhibitions will likely tear up the turf before the premier match begins, resulting in a lower-quality playing surface for the main event." is out of scope – the field quality is irrelevant as to whether the plan will reach its objective of reducing congestion near game time. 
• Choices "Some fans of the Plymouth Soccer Club must travel for several hours to attend matches at the stadium." and "Because of its original design, the stadium used by Plymouth Soccer Club has fewer entryways than any other stadium in the surrounding area.", similarly, do not hinder the plan’s chance of reaching its objective.

Example 2: Department of Energy Spokesman: Energy consumers who pay their own utility bills have a direct financial incentive to use less energy. But in most of our nation's residential rental properties, the owner of the property - not the tenant who directly consumes that property's energy - pays the utility bill. In order to reduce our nation's energy consumption, we should require that tenants be responsible for paying their utility bills in residential rental properties. 
Which of the following is a reason to believe that the plan outlined above will not reach its goal?

a. Most of the country's energy consumption comes from commercial real estate, not residential real estate.
b. When owners of rental properties are responsible for utility bills, they are more likely to ensure that a property's appliances and furnaces are the most energy-efficient versions.
c. Energy bills are calculated not only by the amount of energy used, but also by the times of day during which energy is used.
d. Most rental properties are rented by younger people, and people tend to be more conscious about environmental issues like energy consumption when they are younger.
e. Other nations have had success reducing energy consumption by offering rental subsidies for tenants whose energy usage falls below certain thresholds.

Ans: When owners of rental properties are responsible for utility bills, they are more likely to ensure that a property's appliances and furnaces are the most energy-efficient versions.

Sol: In this Plan/Strategy question, the goal is to reduce a nation's energy consumption, and the plan is to require tenants to be the payers of utility bills (as opposed to the owners of those properties). Remember: with Plan/Strategy questions, two concepts are crucial:
1) Pay close attention to the specific goal, which plays the same role as the conclusion in a classic Strengthen/Weaken question. Trap answers are often related to the general topic but do not affect the specific goal.
2) A better plan does not weaken the provided plan! Your job is only to assess whether this plan will achieve this objective, not whether it's the best plan, the most efficient plan, etc.

• Note that each of "Most of the country's energy consumption comes from commercial real estate, not residential real estate." and "Other nations have had success reducing energy consumption by offering rental subsidies for tenants whose energy usage falls below certain thresholds." suggests a "better plan" - "Most of the country's energy consumption comes from commercial real estate, not residential real estate." suggests that this plan wouldn't be as effective as one that tackled energy usage in commercial real estate and E suggests that rental subsidies could be a better program. But neither directly weakens this plan: as long as less energy is used under this plan, the plan has achieved its goal of reducing energy usage. So "Most of the country's energy consumption comes from commercial real estate, not residential real estate." and "Other nations have had success reducing energy consumption by offering rental subsidies for tenants whose energy usage falls below certain thresholds." may be tempting, but they are incorrect.
• Choice "When owners of rental properties are responsible for utility bills, they are more likely to ensure that a property's appliances and furnaces are the most energy-efficient versions." is correct: if giving the tenants an incentive to use less energy also remove the incentive for the landowners to pursue energy-saving policies, that suggests that this plan may not work at all: it may not result in any energy reduction.
• Choices "Most rental properties are rented by younger people, and people tend to be more conscious about environmental issues like energy consumption when they are younger." and "Energy bills are calculated not only by the amount of energy used, but also by the times of day during which energy is used." are too far from the scope of the current plan and its goal, and are also incorrect. "When owners of rental properties are responsible for utility bills, they are more likely to ensure that a property's appliances and furnaces are the most energy-efficient versions." is the correct choice.

Example 3: According to a recent study, employees who bring their own lunches to work take fewer sick days and are, on average, more productive per hour spent at work than those who eat at the workplace cafeteria. In order to minimize the number of sick days taken by its staff, Boltech Industries plans to eliminate its cafeteria.
Which of the following, if true, provides the most reason to believe that Boltech Industries' strategy will not accomplish its objective?

a. Many Boltech employees chose to work for the company in large part because of its generous benefits, such as an on-site cafeteria and fitness center.
b. Because of Boltech's location, employees who choose to visit a nearby restaurant for lunch will seldom be able to return within an hour.
c. Employees have expressed concern about the cost of dining at nearby restaurants compared with the affordability of the Boltech cafeteria.
d. Employees who bring their lunch from home tend to lead generally healthier lifestyles than do employees who purchase lunch.
e. Boltech's cafeteria is known for serving a diverse array of healthy lunch options.

Ans: Employees who bring their lunch from home tend to lead generally healthier lifestyles than do employees who purchase lunch.

Sol: The strategy outlined in this Weaken problem makes a classic error of correlation vs. causation, assuming that "bringing lunch to work" is a cause of "takes fewer sick days." In actuality, it could be that bringing lunch is an effect of a totally different cause, as 

• Choice "Employees who bring their lunch from home tend to lead generally healthier lifestyles than do employees who purchase lunch." correctly points out. With choice "Employees who bring their lunch from home tend to lead generally healthier lifestyles than do employees who purchase lunch.", the cause of both "brings lunch to work" and "takes fewer sick days" is that generally-healthier people do both - they bring their lunch to work and they take fewer sick days. Forcing someone else - someone less healthy - to bring his or her lunch wouldn't change the other unhealthy habits that lead to extra sick days, so the plan would not work.
• Choice "Boltech's cafeteria is known for serving a diverse array of healthy lunch options." seems like it should weaken the plan (taking away the healthy options at the cafeteria), keep in mind that we already have the evidence that those who bring their lunch take fewer sick days than those who eat at the cafeteria, so those healthy cafeteria options have already been called into question as a driver of fewer sick days.
• Choice "Because of Boltech's location, employees who choose to visit a nearby restaurant for lunch will seldom be able to return within an hour." could very well be correct if the goal were to minimize "time away from one's desk" or something similar, but the goal is specifically called out as "fewer sick days." Being away for a longer period for lunch may well be a problem worth considering, but in the context of this particular goal it is irrelevant.
• Choice "Employees have expressed concern about the cost of dining at nearby restaurants compared with the affordability of the Boltech cafeteria." is similar: it shows a reason why the plan might not be a great plan overall (it could hurt employee morale) but the goal is specifically drawn at "fewer sick days" so that morale is irrelevant to the specific aims in the problem. For similar reasons, choice "Many Boltech employees chose to work for the company in large part because of its generous benefits, such as an on-site cafeteria and fitness center." is also incorrect - while morale may be hurt and people might feel misled (or future recruitment efforts may fall short), the only objective specifically addressed in the problem is "reduce the number of sick days" so choice "Many Boltech employees chose to work for the company in large part because of its generous benefits, such as an on-site cafeteria and fitness center." is not relevant.