This Inference problem demonstrates the importance of the "Must Be True" standard for GMAT inferences. With Inference problems, you want to attack the answer choices looking to exploit small flaws, and eliminate accordingly.

Choice "People whose diets are high in vitamin C are less likely to contract periodontitis than those whose diet are low in vitamin C." is too general and emphatic a conclusion. Even though vitamin C itself can help to prevent or treat these conditions, one cannot conclude that those who consume vitamin C will be less likely to contract those conditions. Consider a hypothetical: it could be that vitamin C alone would help, but that vitamin C is often present in sugar-containing foods and most people with high vitamin C levels are also guilty of a high sugar diet that leads to even quicker gum disease. Choice "People whose diets are high in vitamin C are less likely to contract periodontitis than those whose diet are low in vitamin C." may very well be true, but if you can create a hypothetical with a case in which it would not be true, you can eliminate it.

"Periodontitis is a condition only contracted by those who have previously contracted gingivitis." is similar: it seems like it's probably true, since you're told that gingivitis "can lead to periodontitis" but you don't know that it's the only thing that can lead to the condition (as choice "Some people suffering from periodontitis do so without having contracted gingivitis." suggests). Since you're unsure whether gingivitis is the only cause, or just one of multiple potential causes, you can eliminate both "Periodontitis is a condition only contracted by those who have previously contracted gingivitis." and "Some people suffering from periodontitis do so without having contracted gingivitis.".

Choice "A periodontitis treatment plan that does not include vitamin C is less effective than a plan that does." is also not proven. There may be other plans that do not include vitamin C but that are extremely effective. Note the language in the last sentence of the stimulus, that vitamin C "can help to treat periodontitis." "Can help" is soft language that leaves plenty of room for another treatment program to be even more helpful.

Choice "Increasing the amount of vitamin C in one’s diet has helped some periodontitis patients reduce the severity of that condition." is correct, in large part because of similarly soft language. If vitamin C can help treat the condition, that means that it must have helped at least some patients in treatment. That's an easy bar to get over, and since you know for a fact that vitamin C is helpful, you can clear that bar. Choice "Increasing the amount of vitamin C in one’s diet has helped some periodontitis patients reduce the severity of that condition." is correct.

The stimulus states that "...health insurance companies paid for a smaller percentage of claims last year than they did ten years ago." This means that the companies had a greater percentage of unpaid claims last year. Put another way, they had a smaller percentage of unpaid claims ten years ago, which is what choice "the percentage of health insurance claims that were unpaid was less than last year's percentage." says.

Choice "fewer people made health insurance claims than was the case last year." is incorrect because the number of people making claims is never mentioned. One person can make several claims, so we cannot draw any inferences about the number of people.

"more claims were not paid by insurance companies than were not paid last year." is wrong because the overall number of claims and the percentage of claims not paid were both lower ten years ago. Since they were both lower, their product (Total * Percentage) would also be lower, disproving the statement that more claims were not paid.

Answer "health insurance companies paid a greater percentage of their claims than they paid twenty years ago." is incorrect because we do not have any way of knowing the difference in the percentage of claims paid for these two periods (ten years ago versus twenty years ago).

Answer "profits made by health insurance companies were similar to profits made by health insurance companies last year." is incorrect since we already know that the companies have compensated for paying more real dollars by hiking their rates, but there are too many other factors involved in determining profit to make this comparison.

Whenever you are asked to make an inference from an argument presented on the GMAT, remember that inferences don't need to be interesting or surprising - they only need to be guaranteed.

The argument here states that a television network has been criticized for not giving as much time to climate change deniers as it does to those who believe in climate change even though they do give equal time to all sides of the debates surrounding other issues like tax reform and immigration. The network claims that this is because they only give equal time if one side of the debate cannot be definitively proven by science.

Since the network does not give equal time to both sides of the climate change debate, that means that people at the network believe that it fits the exception given and that one side (the side that believes in climate change) has been definitively proven by science, which matches answer choice "The television news network believes that the existence of climate change has been definitely proven by existing scientific research.".

Among the other answers, "The television news network believes that it is important to avoid debate on scientific discoveries." can be discarded because while the network does not give equal time for all sides of the debate in some cases, it does not provide a blanket dismissal of debating all scientific discovery. Choice "There are no effective counter arguments against climate change that might sway viewers to believe that climate change is not occurring." can be eliminated since while the network believes the science has been settled, this is not the same thing as claiming that no one will be swayed by the arguments against climate change. Choice "No individuals who spoke on the network and who did not believe climate change was occurring were scientists." is a bit harder to eliminate since the stimulus tells you that the people who believe that climate change is occurring are scientists, but it doesn't specifically say that the individuals who don't believe in climate change aren't scientists, so "No individuals who spoke on the network and who did not believe climate change was occurring were scientists." can be eliminated. Choice "If the news network gave the same time it gave to scientists to individuals who don’t believe in climate change, it would increase its ratings." can also be eliminated since even though some people criticize the network for its current policy, it is unknown how a change in policy would affect overall criticism of the network (and in turn how that would effect ratings).

The correct answer to this question is "It is not possible for any top computer hacker to gain access to a computer equipped with the recognition software solely by virtue of skill in replicating the structure of fingerprints.". This is an INFERENCE question, requiring the test taker to choose the correct answer that must be true based on the information provided in the stimulus. "Use of the recognition software is largely impractical due to the time it takes to record and analyze a fingerprint." is incorrect as the passage provides no information with regard to the speed of recording and analyzing the fingerprint; as such, no related conclusion can be drawn. "Computers equipped with the recognition software will soon be installed in most financial firms that deal with sensitive electronic information." is incorrect as the passage provides no information with regard to the installation of computers that possess the software in specific locations; as such, no related conclusion can be drawn. "It is not possible for any top computer hacker to gain access to a computer equipped with the recognition software solely by virtue of skill in replicating the structure of fingerprints." This is the correct answer. The passage states that the software detects more characteristics than those that the most successful hackers are able to duplicate; as such, we can conclude it would be impossible for any top hacker to gain access to a protected computer solely by replicating one of multiple characteristics analyzed by the software. "Fingerprint recognition software has taken many years and tremendous investment to develop and perfect." is incorrect as the passage provides no information with regard to the time and investment costs associated with the development of the software; as such, no related conclusion can be drawn. "The fingerprint recognition software is so sensitive that many authorized users are often denied legitimate access." is incorrect as the passage provides no information with regard to errors produced by the software; as such, no related conclusion can be drawn.

Because this is an Inference question, the degree of proof for the correct answer is that the correct answer MUST BE TRUE. Because of that:

Choice "Unless the minimum wage increases, MacDowell’s will continue to remain profitable." is incorrect because you're not told what happens if the minimum wage does not increase. This prediction is hard to make, then: suppose the minimum wage stayed flat but a disease was traced to MacDowell's ingredients or a fire burned down its top-grossing store. There are plenty of ways for profitability to be cut even if the minimum wage stays flat.

Choice "If the minimum wage increases, MacDowell’s will no longer be able to remain profitable." is incorrect because it goes too far. You know that profitability will decrease, but not that it will go away entirely.

Choice "MacDowell’s will see its profitability increase if the minimum wage does not increase." is incorrect for similar reasons to choice "Unless the minimum wage increases, MacDowell’s will continue to remain profitable.". There are plenty of factors aside from the minimum wage that could decrease profitability, so choice "MacDowell’s will see its profitability increase if the minimum wage does not increase." is not necessarily true.

Choice "MacDowell’s will be unable to maintain its current profitability if the minimum wage increases." is correct. Because you're told in the argument that, of the two options that would face MacDowell's in the event of a minimum wage increase, both will decrease profitability, you know it to be true that a wage increase will cut profitability.

Choice "If MacDowell’s sees a reduction in its profitability, that means that the minimum wage has increased." is incorrect for similar reasons to "Unless the minimum wage increases, MacDowell’s will continue to remain profitable." and "MacDowell’s will see its profitability increase if the minimum wage does not increase.". Plenty of other factors can lead to a decrease in profitability, so that decrease on its own does not allow you to infer that it was specific to a minimum wage hike.

This is an Inference question. In isolation, the phrase in the question stem, “most strongly supports”, could hint at either a Strengthen question or an Inference question. However, when we take the stem in its entirety, the structure of the problem begins to unfold. Remember: premises always support conclusions. Thus, if the information in the answer choices supports the argument above, the answer choices must be premises and the conclusion is found in the argument (leading us to believe the problem is a Strengthen question.) On the other hand, if the information in the body of the question supports the answer choices below, the argument’s conclusion must be found in the answer choices (leading us to believe the problem is an Inference question.) Since the question stem indicates that the information “above” is supporting answer choices below, the answer choices must be potential conclusions. This must be an Inference question.

Two primary insights can be gleaned reading the body of the question. First, since we are looking at an Inference question, our first line of defense is the “no new information” filter. Remember that valid conclusions must always (not just sometimes) be true, and therefore must be based entirely on the information found in the premises. Conclusions containing new information not found anywhere in the argument may or may not be true. The second insight is closely linked to the first. Throughout the entire body of the question, a lot of fuzzy, non-specific words are used: “most pain relievers”, “some people”, and “many people.” They describe subgroups of the total, and are very nebulous, especially when you contrast such phrases with “all pain relievers” or “all people.” Therefore, valid conclusions that go beyond these vague categorizations may or may not be true. Believing you can conclude something about “all people” when you only know about “some people” is a logical error known as overgeneralization. Once we recognize this trick of the Testmaker, it becomes relatively easy to spot many of the wrong answer choices.

Answer choice “A physician should not advise any patient to take any pain reliever for a period of longer than 7 consecutive days.” is a classic example of overgeneralization. Notice how this conclusion focuses on “any patient” taking “any pain reliever.” The body of the question only tells us about “most people” and “most pain relievers”. This conclusion goes beyond what we know, and therefore is not necessarily true.

Answer choice “People who are sensitive to one type of pain reliever should not attempt to use a different pain reliever.” includes new information not contained in the body of the question. The evidence in the top part of the question contains nothing about people being “sensitive” to one type of pain reliever. Therefore, we cannot make a conclusion about something we don’t have information on. Answer choice “People who are sensitive to one type of pain reliever should not attempt to use a different pain reliever.” is not necessarily true.

Answer choice “At least some people who take pain relievers for longer than 7 days will experience side effects. contains no new information, and remains within the fuzzy scope of the original statements. The body of the question tells us that “many people” who take painkillers for longer than 7 days experience side effects. The conclusion that “at least some people” will experience side effects is well within the information given. “At least some people who take pain relievers for longer than 7 days will experience side effects.” is basically a restate of information already given, so we can clearly conclude it must be true. “At least some people who take pain relievers for longer than 7 days will experience side effects.” is the right answer.

The conclusion in answer choice “Any side effects experienced by a patient who has taken a pain reliever for fewer than 7 consecutive days cannot be the result of the pain reliever.” also uses extreme scope limiters not justified by the original evidence. It refers to “any side effects” that “cannot” be the result of pain relievers. This goes well beyond the scope. The problem only tells us about side effects caused by a subset of pain relievers. It makes no mention of side effects not caused by pain relievers. Answer choice “Any side effects experienced by a patient who has taken a pain reliever for fewer than 7 consecutive days cannot be the result of the pain reliever.” fails the “no new information” filter. We cannot make a conclusion about something we don’t have information on. Answer choice “Any side effects experienced by a patient who has taken a pain reliever for fewer than 7 consecutive days cannot be the result of the pain reliever.” is not necessarily true.

Answer choice “Anyone who wants to maximize their natural health and well-being should avoid pain relievers entirely.” contains all sorts of new information not contained in the original evidence. The body of the question makes no mention on how to “maximize your natural health and well-being”, nor does it give us any criteria for when we should avoid pain relievers. (For example, could it be possible that the advantages of taking pain relievers could outweigh the side effects, even if we had to deal with these negative consequences?) “Anyone who wants to maximize their natural health and well-being should avoid pain relievers entirely.” cannot be a valid conclusion.

Whenever a GMAT question asks for something that can be "properly inferred" from a critical reasoning argument, remember that your job is to fully understand the argument presented and then look for the answer choice that is guaranteed by the information presented. Remember, the information doesn't have to be interesting - it just needs to be something that must be true given the information presented.

In this case, you are told there's no correlation between the percentage of an individual's income spent on healthcare and the quality of healthcare they receive. (Further, if it did exist, the argument states that either individuals who spend a greater percentage of their income on health insurance would get better or worse quality of care.)

The only real information that you have here is the fact that increased (or decreased) spending on health insurance as a percentage of income does not "necessarily indicate quality of care." You don't have any information on absolute amounts spent on health insurance or about the health insurance itself. From this, you can eliminate "If individuals receiving free or reduced cost health insurance from the government were removed from the sample, there would be a strong correlation between cost and quality of care.", which deals with eliminating a particular type of health insurance from the sample and "Looking at the dollar amount spent on health insurance rather than the percentage would show a correlation between amount of money spent and quality of care.", which deals with absolute dollar amounts. Choice "It is probable that individuals who spend more on health insurance in fact get a lower quality of care than do those who spend less on health care." can also be eliminated since you are told that there is no correlation in either direction.

Between "Individuals who spend the greatest percentage of their income on health insurance never receive high quality of care from medical providers." and "Reducing an individual’s spending on health insurance as a percent of their income will not necessarily lead to lower quality of care.", choice "Individuals who spend the greatest percentage of their income on health insurance never receive high quality of care from medical providers." can be eliminated since there is just no way to prove that individuals who spend a large percentage of their income on health insurance never get quality care from medical providers - the entire point of the argument is that there is no correlation.

Choice "Reducing an individual’s spending on health insurance as a percent of their income will not necessarily lead to lower quality of care." must be correct. If there is no correlation between spending on health insurance as a percentage of income, then reducing spending on health insurance as a percent of income may or may not affect quality of care. The words here "will not necessarily lead to lower quality of care" are particularly important, since it links back to the argument that there is just no way to tell.

This is an inference question. The correct answer must be true. From the stimulus we know that the jury is not supposed to consider the fact that a defendant does not testify as evidence of guilt or innocence. And yet, jurors do take the refusal to testify as evidence of guilt. This means that choice "The fact that a defendant refuses to testify is sometimes unfairly considered by a jury as evidence of guilt." must be true, the fact that a defendant refuses to testify is unfairly seen by some jurors as evidence of guilt.

Choice "Most defendants who refuse to testify in their trials are, in fact, guilty." could be false, there is no indication of whether those who refuse to testify are guilty. Choice "The rules should be modified to require defendants to testify regardless of their guilt or innocence." indicates what “should” happen. This is a recommendation and is not something that must be true, even if it does seem logical. Choice "A defendant would sometimes be better served by testifying at trial rather than by choosing not to testify." could be true, a defendant might be better served by testifying, but it could be false as well. This is a prediction and it is very difficult for a prediction to be must be true. Choice "Some jurors refuse to take a defendant’s refusal to testify into consideration when deciding guilt or innocence." seems very plausible. Jurors are not supposed to take a defendant’s not testifying into account. It is logical to think that at least some jurors would follow this rule. However, it is not clear that this is the case. This does not reach the standard of must be true. The stimulus still allows the possibility that every juror takes the fact of not testifying into account.

This inference question makes you choose between a guaranteed (and almost boring) answer choice and answer choices that tend to over-generalize from the information given in the prompt. As with any inference question, it is important to pay careful attention to word play within the answers. In this case, it forces you to differentiate between two groups: ‘Top 50’ business schools in general and the subset of ‘Top 50’ business schools discussed in the prompt.

For answer choice "Accepting over 30 percent of applicants can help a business school move into the 'Top 50'.", raising the acceptance rate has nothing to do with the quality of the school or its applicants. The argument doesn’t give any information about what it takes to become a top 50 School – eliminate "Accepting over 30 percent of applicants can help a business school move into the 'Top 50'.".

Although "Most students whose GMAT scores are below 650 tend to have undergraduate grade point averages under 3.4." is tempting, the argument does not make a connection between all students whose GMAT scores are below 650 and who have grade point averages under 3.4. While this connection might be true for the students admitted to the schools discussed, the argument doesn’t address GMAT takers in general, so this inference is not guaranteed.

Similarly, answer choice "'Top 50' business schools tend to accept students with undergraduate grade point averages under 3.4." over generalizes and tries to extrapolate general tendencies among all ‘Top 50’ business schools from the information given about one fourth of that group. Because there is no indication that you can extrapolate from the information given, "'Top 50' business schools tend to accept students with undergraduate grade point averages under 3.4." is not a proper inference.

Answer choice "Work experience is not the most important criterion for admission to a 'Top 50' business school." also makes the mistake of over-generalization. While some ‘Top 50’ schools admit students without much work experience, that does not mean that work experience isn’t the most important criterion for any ‘Top 50’ business school, as suggested in "Work experience is not the most important criterion for admission to a 'Top 50' business school.'.

Answer choice "It is possible for a business school whose accepted students have average GMAT scores under 650 to be 'Top 50'." is almost guaranteed by the argument. If admitted students at 25% of the ‘Top 50’ business schools tend to have scores around 650, it is possible that the average for those schools will be around 650. Since "It is possible for a business school whose accepted students have average GMAT scores under 650 to be 'Top 50'." only requires that it be possible, it is a proper inference and is the correct answer.

The argument states that there are two unintended results of spraying chemicals in the home. Chemicals kill spiders, which would normally kill other insects found in the home. Second, insects become resistant to the chemicals over the course of generations. The correct answer will solve (or at least mitigate) one of these two problems, thus increasing the effectiveness of the chemical sprays (the goal of the question). Remember that for any inference question that inferences must be guaranteed. This may mean that they are not interesting and may add information that seems almost identical to what is given in the argument.

Remember that it’s often to find what is wrong with an answer choice than finding what works about it. Answer choice "Using only sprays that are more chemically stable" doesn’t address anything to do with the spiders or insects becoming resistant, so it can be eliminated. Alternating the chemical spray used "Alternating the use of a variety of chemical sprays used" does address the insects becoming resistant. This will improve the effectiveness of the chemical sprays, so "Alternating the use of a variety of chemical sprays used" is the correct answer.

For completion, make sure that "Increasing the amount that is sprayed", "Spraying only a portion of the house at a time", and "Planting trees outside of the house to attract certain insects that typically are resistant to chemical sprays" can be eliminated. "Increasing the amount that is sprayed" can be eliminated because increasing the amount sprayed doesn’t address the problem of resistance and may make more spiders die. "Spraying only a portion of the house at a time" can be eliminated since, while spraying one portion of the house at a time might seem like it might address the issue of resistance, it doesn’t. Planting trees that house resistant insects "Planting trees outside of the house to attract certain insects that typically are resistant to chemical sprays" would be counterproductive.