Strengthen/Weaken Critical Reasoning - GMAT Verbal

This argument features issues with two extremely common logical fallacies: 1) correlation vs. causation and 2) data pools that aren't necessarily comparable. If you see these elements in the gap in logic, you can anticipate the right answer.

First, notice that in the 20 years between arrest statistics that the official cites, many things could have occurred other than the laws she cites. What if, for example, alcohol tariffs made the price so exorbitant that everyone just quit drinking? Or the city built a system of canals and everyone just kayaks around town now? There could well be other causes for the statistic - the laws might be correlated with the time period, but did they really cause the outcome?

Second, notice that the use of actual-number data (25,000 arrests vs. 18,000 arrests) doesn't necessarily tie to the conclusion. Yes the number of arrests down (and the total population is up), but the conclusion is that the legislation was successful in "preventing motorists from driving under the influence." Since "motorists" is a subset of the total population, you'd really want to see a statistic that isn't just total number of arrests, but something more like arrests per 1,000 motorists" - a statistic that accounts for the fact that the number of motorists could be way down (in which case "motorists" - those who still drive - might still be driving under the influence quite frequently, but the overall statistic is down because there are simply much fewer drivers).

Given those errors in the argument, choice "Increased access to public transportation and ride-sharing applications has cut the number of drivers in the province by more than half." is correct - it shows that the number of motorists is down, and supplies an alternate cause for the drop in the number of arrests. People are using Lyft and taking the train, not driving anymore.

Among the other choices:

"The population in her province has increased at a lower rate than the populations of neighboring provinces." is irrelevant, as whether the population has grown at a high or low rate compared to other provinces, the fact remains that the population has still increased. (And really what you want to know is the number of drivers/motorists)

"The new legal measures have increased the province's law enforcement costs at nearly twice the rate that tax receipts have increased." seems like it should matter (is this a good use of money?) but remember that the specific conclusion is only about whether the laws worked, not about whether they were a wise use of funding. Always stay within the specific scope of the conclusion!

"Since 1998, the number of lawyers focusing on defending those arrested for driving under the influence has more than doubled." misses the mark because of its timing - the statistic used in the argument is about arrests, and notes that this intervention of lawyers occurs after the arrests have already taken place. If lawyers were acting before the arrests, that might suggest that the lawyers are causing the reduction in the number even though people are still drinking and driving, but that's not the case here - the lawyers in "Since 1998, the number of lawyers focusing on defending those arrested for driving under the influence has more than doubled." don't come into the picture early enough to explain away the number of arrests.

And "The number of restaurants and pubs permitted to sell alcohol in the province has increased since 1998 at approximately the same rate of the province's population." is similar - if the number of establishments serving alcohol were way down that might be part of an alternate explanation for the reduction in arrests, but with the number of restaurants and pubs serving alcohol increasing, that's not the case.

As with any weaken question, your first goal should be to understand the argument presented and find the gap between the information given and the conclusion presented. In this argument, you are told that a study claims that not eating genetically modified foods (GMOs) leads to lower rates of type 2 diabetes and heart disease because people who didn't eat GMOs tend to develop type 2 diabetes and heart disease at a lower rate than do people who do eat GMOs.

The gap here is in the difference between correlation and causation. While there is a correlation between the behavior (not eating GMOs) and the outcome (not getting type 2 diabetes or heart disease), there is nothing that proves the outcome is due to the behavior. What if non-GMO foods were only available to individuals who were wealthy or who belonged to a specific ethnic group that developed both diseases at lower rates? The correct answer will exploit the gap between correlation and causation.

The only answer choice to do this is "Individuals who do not eat genetically modified foods also tend to exercise and make other healthy lifestyle choices associated with a decreased risk of both diseases.". If individuals who don't eat GMOs also engage in other activities known to lower the risk of both diseases, then it's impossible to tell if their decreased risk is due to the fact that they don't eat GMOs or the fact that they engage in these other activities. Maybe the cause of both (not eating GMOs and decreased risk) is their lifestyle, and those two effects are just correlated.

Among the other answers, "Genetically modified foods also tend to be organically grown, a process that uses fewer pesticides and artificial fertilizers than does conventional agriculture." can be eliminated because there is no way to link the practice of using pesticides or artificial fertilizers to diabetes or heart disease. Choice "Type II diabetes and heart disease are often exacerbated or triggered by poor diets, especially those high in processed grain-based foods and fat-heavy meat products." can be eliminated since it does not address anything to do with the conclusion, which is specifically about genetically modified foods. Choice "It is possible that some individuals could be naturally resistant to developing both type 2 diabetes and heart disease regardless of diet." can also be eliminated for the same reason - there is no reason that these individuals wouldn't have shown up in both groups. Choice "Other studies have examined the effects of organic food on the risk of developing both diseases, but not on the effects of genetically modified food." can be eliminated as well since whether other studies have looked at this issue doesn't impact whether or not the conclusion is correct.

If you look for the logical flaw in the argument of this Strengthen question, you should see that it is one of generalization. Based on exactly one data point - a particular soccer star is less famous than 20 different basketball players - the argument draws the general conclusion that soccer players are not the most well-known athletes in the world. But Fabricio is only one player: if this were a Strengthen question you would want to show that he is an outlier on the less-famous side (meaning that most players are far more famous than he is, so this one data point is less relevant). But since this is a Weaken question, you want to show that Fabricio is one of the most famous soccer players, so that all other players are even less famous.

Choice "Fabricio is the most well-known soccer player in the world." does exactly that, and is therefore correct: if Fabricio is the most famous soccer player, and he's less famous than 20 basketball players, then the conclusion that soccer players are not the most famous athletes is a lot more likely - Fabricio isn't the one not-famous outlier while all the others are very famous. "Fabricio is the most well-known soccer player in the world." is correct.

Among the other answer choices: choice "AC Camarillo has won its league's championship the past three consecutive seasons." doesn't link Fabricio or AC Camarillo to being well-known. If AC Camarillo is a champion in a lesser-known league, then Fabricio isn't necessarily a particularly well-known player; if the team is the champion of an extremely popular league, then it's more likely that he's among the most well-known (but you still don't know for sure).

Choice "Fabricio is less well-known than the stars of several other professional soccer teams." weakens the argument by going the opposite direction of "Fabricio is the most well-known soccer player in the world." and saying that Fabricio isn't among the most famous players in the world. Choice "The most well-known basketball players are not always the best players on their teams." would slightly strengthen the argument if it were specific to the 20 players more famous than Fabricio, as then there would be even more basketball players who are more famous than Fabricio. But since it's a generic "the most famous players are not always the best on their teams" it doesn't add any more players more famous than Fabricio and therefore has no direct bearing on the argument. And choice "No professional basketball players are also professional soccer players.​" is similarly generic and therefore doesn't add any new data to further the argument (if it were that the most famous basketball players ARE also soccer players then it would have a direct bearing, but as written it does not).

This weaken problem features a common gap in logic: a fact is given (the cross-country GPA is higher than the average GPA) and then one plausible explanation is given as the only explanation for why that fact is true. This is essentially mixing correlation for causation: because two things occur together (runners have a lot of time to think, and runners have high GPAs, the time to think must cause the GPA). The best ways to weaken one of these arguments are to find an alternate explanation or to show that the causation is reversed (it's not that time spent running causes the high GPA, but rather the high GPA leads people to run).

And choice "The cross-country team is among the few teams that do not require a tryout, making it a popular activity for high-achieving students who want to list a sport on their college applications." does exactly that - it suggests that students with high GPAs are more likely to join the cross-country team. It's not that the running makes them better students, but instead good students tend to go toward running as a way to add an extracurricular activity to their application profile. That's why choice "The cross-country team is among the few teams that do not require a tryout, making it a popular activity for high-achieving students who want to list a sport on their college applications." is correct.

Among the wrong choices:

Choice "Cross-country running is more strategic than many realize, requiring runners to expend mental energy thinking about race tactics." should be tempting, but it does not directly attack the notion that runners have a lot of time to think. An activity can be strategic and still allow time to think. Choices "Many cross-country runners are also members of the track-and-field team, for which the average grade point average is actually lower than that of the school as a whole.", "Because the nearest cross-country trails are a long distance from the school, cross-country is one of the most time-consuming activities the school offers.", and "The cross country team's average grade point average has dropped each of the last three years." each try to attack the premise, making you think that the GPA shouldn't be as high as it is. "Many cross-country runners are also members of the track-and-field team, for which the average grade point average is actually lower than that of the school as a whole." does this by grouping cross-country runners with the other track-and-field athletes, for whom the GPA is lower. But we already know that the cross-country GPA is high, so it doesn't matter which other groups you could pool them with to lower their grades. Choice "Because the nearest cross-country trails are a long distance from the school, cross-country is one of the most time-consuming activities the school offers." similarly tries to provide a reason why you wouldn't think that the GPA would be high (it's such a time-consuming activity!) but again that doesn't matter - the GPA is high, so we're just trying to determine the cause. And choice "The cross country team's average grade point average has dropped each of the last three years." tries to do this by showing that the GPA is dropping, but again it's already been established that it's higher than average, and your only job is to determine why.

In this argument, there is a correlation between brain size and activity of the ant – those ants that gather nourishment (which tend to be older) have larger brains than those ants that nurture larvae (which tend to be younger ants). Because of this correlation, the author concludes that the cause for this difference in size must be the increased cognitive skills required for gathering. But where is the proof for this? Perhaps there is some other attribute relating to the ants that perform these different tasks and that is the reason for the difference. What if quite simply, older ants (which perform the gathering) have larger brains than younger ants (which perform the nurturing)? Then it simply has to do with age NOT the tasks they are performing. To weaken this argument, you are looking for some other plausible explanation for the different size brains and "The brains of older ants that are not involved in gathering nourishment are the same size as those counterparts of the same age that do gather nourishment." gives that perfectly, as it suggests that indeed the difference might be explained by age alone.

For "Ants that have spent more time gathering nourishment do not have considerably larger brains than do ants that have spent a much shorter time gathering." – this does not necessarily weaken the argument. The activity the ant performs could indeed be causing the difference, but at a certain threshold, more gathering does not further increase brain size. "Ants that have spent more time gathering nourishment do not have considerably larger brains than do ants that have spent a much shorter time gathering." can be true and it does not hurt the core position of the argument. Likewise for "The brains of older ants that stop gathering nourishment to take on other tasks do not become smaller.", the author is just stating that the INCREASE in brain size is caused by the different activities – if the brain doesn’t decrease in size after stopping the activities it does not affect this conclusion. For "In many species of ants, the brains of older ants are only minimally larger than the brains of younger ants.", the degree of the difference in size is not addressed in the argument so this choice has no impact on the quality of the author’s conclusion. Similarly for "Ants that have to travel farther to gather nourishment do not have considerably larger brains than do ants that do not have to travel far.", the distance traveled is not addressed in the argument, simply what activity the ants engage in. Correct answer is "The brains of older ants that are not involved in gathering nourishment are the same size as those counterparts of the same age that do gather nourishment.".

The key in this problem is to consider some flaw with the trend that the sociologist cites. In other words, what might indicate that the trend will not continue? Consider the following scenario: 10 years ago, most women who would normally have married at 22 start waiting to get married until they are forty. Over the next twenty years, the marriage rate would go down dramatically because women are waiting to get married (and the average marriage age is going up). However, when they do decide to get married, the rate will go back up again. If this were true it would show a huge flaw in the sociologist’s reasoning so "The average age of marriage has increased dramatically in the past 20 years." is correct. For "Today’s divorce rates are expected to rise dramatically over the next 40 years." and "More women are expected to get married for a second and third time in the next 40 years." divorce rates and second/third time marriages are unimportant because the argument is only about first time marriages. "Many women are deciding to simply live with their partners rather than get married." and "Marriage is much less likely to occur today for the first time than it was in the 1960’s." would not indicate a flaw as they both seem to support the sociologist (that is the trend that marriage is disappearing). Answer is "The average age of marriage has increased dramatically in the past 20 years."

The epidemiologist’s argument improperly assumes that the cancer death rates were similar in the two towns ten years ago. While the rates in Maple Grove have INCREASED much more than in Fernland, what if they were much lower to begin with. Just because the rate has increased more in Maple Grove, it could easily be lower today than in Fernland. Answer choice "Whether Fernland and Maple Grove had similar cancer death rates 10 years ago." properly points out this assumption and is thus the correct answer. For "Whether the population in Maple Grove has increased dramatically in the past decade.", population growth is unimportant because it is a per capita rate. The smoking issue is a red herring in this problem (tries to steal your attention from the major data problem), so "Whether smoking is the primary cause of cancer in Fernland." and "Whether Maple Grove has ever introduced an anti-smoking initiative." are both wrong. For "Whether most cancer victims in Maple Grove survive more than 10 years.", the length of survival is also immaterial to the major data problem isolated above. Answer is "Whether Fernland and Maple Grove had similar cancer death rates 10 years ago.".

As you deconstruct this argument, you should notice a classic case of mistaking correlation (two things occur together) for causation (one causes the other). Here you're told that people who exercise regularly have a lower incidence of respiratory illness, and then the conclusion is that regular exercise helps prevent respiratory illness.

But why can't that be the other way around? Whenever a question is structured as "X and Y happen together, so X likely causes Y" you should be on the lookout for an answer choice that suggests that, actually, Y is the thing that causes X.

Answer choice "People with respiratory illnesses are generally told by doctors that they must limit or cease their aerobic exercise routines." here supplies exactly that: if people who have respiratory illness are unable to exercise, that's a possible reason for the statistics (exercise and respiratory health occur together) to be true. So by providing an alternate explanation for the premises, "People with respiratory illnesses are generally told by doctors that they must limit or cease their aerobic exercise routines." shows that the conclusion is not necessarily true. "People with respiratory illnesses are generally told by doctors that they must limit or cease their aerobic exercise routines." is correct.

"Some respiratory illnesses are hereditary and therefore minimally affected by lifestyle choices." is incorrect because the conclusion is so soft, that exercise "can be helpful in preventing" respiratory illness. Even if some respiratory illnesses cannot be prevented, choice "Some respiratory illnesses are hereditary and therefore minimally affected by lifestyle choices." does not prohibit exercise from preventing other respiratory illnesses. Note also that "Some respiratory illnesses are hereditary and therefore minimally affected by lifestyle choices." says that the hereditary respiratory illnesses are minimally affected by lifestyle choices. "Minimally affected" still allows for lifestyle choices to have an impact, which is consistent with "can be helpful" in preventing these illnesses.

"The amount of air pollution, a common cause of respiratory illness, has increased dramatically since the 1950s." and "The lengths of the average workday and commute have increased markedly since the 1950s, leaving the average person with less time for aerobic exercise." are wrong for similar reasons: they are each overruled by the facts, which state that exercise and a lack of respiratory illness have remained correlated over time, even if respiratory illness is increasing due to pollution "The amount of air pollution, a common cause of respiratory illness, has increased dramatically since the 1950s." or people in general are exercising less "The lengths of the average workday and commute have increased markedly since the 1950s, leaving the average person with less time for aerobic exercise.". You still have facts from the argument that those who do find time to exercise have less respiratory illness than those who do not, so "The amount of air pollution, a common cause of respiratory illness, has increased dramatically since the 1950s." and "The lengths of the average workday and commute have increased markedly since the 1950s, leaving the average person with less time for aerobic exercise." are countered by the given information.

"Recent studies have debunked the conventional wisdom that aerobic exercise is an effective preventer of heart disease." misses the specific scope of the conclusion, which is only about respiratory illness. The fact that exercise doesn't prevent heart disease doesn't factor in to a discussion about respiratory issues. Because heart issues and respiratory issues are two completely different categories, "Recent studies have debunked the conventional wisdom that aerobic exercise is an effective preventer of heart disease." does not directly address the conclusion about respiratory issues.

An important gap in logic on this question exists between premises: we’re told that if a parcel isn’t SCANNED by 4:30, it will not be included for overnight delivery. And we’re told that if the prototypes in the package are not received by the next day, the client will cancel its account. The concluding sentence says that because James DROPPED OFF the package by 4:00, ahead of the 4:30 SCANNING deadline, the company will not lose the account.

Now, notice the big gap here between “DROPPED OFF” and “SCANNED” - is it sufficient to say that because James dropped off the package it will definitely be scanned in time? Dropped off and scanned are two different things. So the answer “Any parcel dropped off before the overnight shipping deadline will be scanned prior to the deadline” is important to connect those dots.

Recognize that the argument contains other gaps, too: the client wants the prototypes by the next morning, but does “scanned for overnight delivery” guarantee “received by morning?” It does not, but no answer choices deal with that gap in logic.

The argument jumps from the idea that these utilities are included for sales reasons to suggesting that they save the computer manufacturer money. Something to link the function of these programs to savings is necessary -- and that is exactly what answer choice "Computer viruses, disk fragmentation, and out-of-date applications are three major sources of warranty claims against computer manufacturers." offers. It is the correct answer. Answer choice "Surveys indicate that free software packages are very important to consumers." may initially appear attractive because of the original statement that free software is included to drive sales, but the argument focuses on cost savings to the manufacturer. Answer choices "Many anti-virus programs offer little, if any, real protection." and "Disk defragmentation is an important routine task that should be performed at least once per month." offer interesting but irrelevant information. Answer choice "Even though computer manufacturers buy these utility programs in bulk, they are still a significant cost to the manufacturer." would, if anything, weaken the argument.

In this Weaken question, the conclusion is that type 1a supernovae are an effective way of measuring distances. The reason is that they have a predictable brightness that fades over distance in a predictable way. Observing and measuring this brightness then allows the distance to be reconstructed. If answer choice "Large clouds of interstellar dust and ionized hydrogen can absorb the light emitted by type 1a supernovae.", the correct answer, were true, however, external factors could create significant variations in the way that the light is observed from Earth, and the use of the brightness observations to gauge distance would seem to be unreliable. Answer choices "Type 2 supernovae are discovered to be even more dramatically variable in their brightness than previously thought." and "Some supernovae exhibit very unusual spectral classifications and changes in brightness, and do not fit into the existing categories." talk about other sorts of supernovae which are not the type we are considering and are, therefore, out of scope. Answer choice "Models explaining the causes of type 1a supernovae are altered to include an updated understanding of the role played by carbon fusion." discusses the model explaining how the supernova works but says nothing about modifying the predictions of how bright the explosion is. Answer choice "A new telescope is able to measure the brightness of several thousand type 1a supernovae with an unprecedented level of precision." does not say anything about the results of the telescope and therefore has no effect on the assumption.

In this strengthen question, take careful note of the oil executive's conclusion, which is that the increase in reported oil spills (he concedes this is a fact) has occurred because it is easier to detect small oil spills, not because there are more oil spills. In other words, the total number of oil spills is the same, and the increased number of reports of them is due to the more-frequent reporting of small spills.

Note how correct answer "The number of large and medium oil spills has remained roughly constant over the last three decades." directly strengthens that: if you know (from the argument) that there are more reported spills overall, and you know (from choice "The number of large and medium oil spills has remained roughly constant over the last three decades.") that the number of large and medium spills is unchanged, then the increase has to have come from the reporting of those small spills. "The number of large and medium oil spills has remained roughly constant over the last three decades." limits the increase to the smaller spills, and therefore furthers the executive's argument.

Note that with choice "The size of the average oil spill has decreased over the last three decades.", the conclusion isn't that there are more small oil spills total but that there have been more reported. So the fact that the average spill is smaller doesn't directly relate to the executive's argument. Furthermore, even if the average reported spill were smaller, that doesn't necessarily mean that there are more small spills being reported - it could just be that each of the larger and medium spills reported have been smaller (maybe they were better-controlled than in the past, for example).

Choice "Because of improved logistics, the average distance a barrel of oil travels to its destination has decreased by 40% over the last three decades." might seem to suggest a reason that there are fewer spills (there is less time/space that each barrel spends in transit) but this misses the general purpose of the argument, which relates to the detection of small spills. The argument isn't that there are fewer transportation-related spills, but that the increase in reported spills comes primarily from the detection of smaller spills.

Choices "The cost required to clean up the average oil spill has decreased by over 20% over the last three decades." and "The average oil company spends nearly twice as much today on anti-spill equipment as it spent three decades ago." each attempt to use cost as proxy for safety - "The cost required to clean up the average oil spill has decreased by over 20% over the last three decades." wants you to think that because the cost of cleanup is down, the spills must be less frequent or smaller, but that's not necessarily the reason. Perhaps cleanup technology has just gotten less expensive. Similarly "The average oil company spends nearly twice as much today on anti-spill equipment as it spent three decades ago." wants you to think that because companies are spending more to prevent spills, spills have decreased or stayed the same. But that's not necessarily the case: what if inflation is higher and the companies are spending less in "real" terms and more nominally because of the currency, for example?

Only choice "The number of large and medium oil spills has remained roughly constant over the last three decades.", which is correct, directly relates to the detection of small spills.

Whenever you are asked for an answer choice that will weaken a given argument or conclusion, remember that you should first seek to understand the argument and then you should look to find the gap between the premises of the argument and its conclusion.

You are told here that since 1950 the number of women diagnosed with postpartum depression in Heranita has increased. Because of this, the advocate suggests that the country improve the women's health care system so that women do not have to experience the symptoms of postpartum depression. Already you should see that there are a few gaps here - what if women have symptoms but aren't diagnosed? What differentiates postpartum depression from regular depression?

Only "Until 1970, most doctors were not specific in their diagnoses but instead grouped all types of depression together." addresses one of those gaps. If cases of postpartum depression were once described under the general umbrella of "depression", then it is impossible to know if postpartum depression is in fact on the rise.

Among the other answers, "The amount of spending on women’s health has increased since 1950." can be eliminated since just because women's health has increased, there is no telling whether spending to prevent postpartum depression has increased. "Rates of postpartum depression are not included in official government statistics." can be eliminated since another agency outside the government might keep track of rates of postpartum depression so this doesn't affect the argument. "The minimum threshold of symptoms women experience before they can be diagnosed has increased since 1950." can be eliminated since just because the minimum severity of symptoms required for diagnosis has increased doesn't mean that the rate has not increased. "It is likely that cases of postpartum depression are underreported in Heranita." can be eliminated because it would in fact strengthen the argument posed.

Your goal in this "Explain the Paradox" question is to find a reason why environmentalists would support the expansion of a landfill that comes with groundwater pollution problems over the construction of a new landfill that would come with no groundwater pollution problems. As you anticipate what you would want to see from a correct answer, you might think about:

-What if the new landfill doesn't have groundwater pollution problems, but instead creates other pollution problems?

-What is leaving the old landfill would create even bigger problems than staying there?

Choice "Without continued operation and maintenance, the current landfill's groundwater pollution rate would more than double. " works well with the second option: if leaving the current landfill would create a much bigger environmental problem than staying there would, that is a reason that those who care about the environment would vote to stay. Choice "Without continued operation and maintenance, the current landfill's groundwater pollution rate would more than double. " is correct.

Choices "Several recent ecological studies suggest that the rate of pollution from the current landfill is lower than had initially been reported." and "Groundwater pollution is less of a concern in Sturgeon County than is air pollution from the county's coal-fired power plants." may be tempting, but each comes with a significant flaw. Note that "Several recent ecological studies suggest that the rate of pollution from the current landfill is lower than had initially been reported.", while reducing the impact of the pollution problem with the current landfill, still leaves the ballot proposals as a comparison between "some pollution" and "no pollution," so you still don't have a reason that the environmentalists would pick "some" when "none" is an option. And while choice "Groundwater pollution is less of a concern in Sturgeon County than is air pollution from the county's coal-fired power plants." may seem to hit the standard of "what about other types of pollution other than just groundwater?" note that the argument doesn't provide any reason to suspect that the new landfill would create more air pollution. With all known information, it's still a comparison between "some pollution" and "no pollution."

Choice "Polling data indicates that the new landfill proposal is unlikely to pass without support from prominent environmental activists. " is irrelevant - what the polls suggest is no reason for the environmentalists to choose pollution over no pollution. And choice "The site of the proposed new landfill is privately-owned land that the county would have to purchase during a period of high real estate values." is carefully invalidated by the phrase "same amount" in the argument - if each plan costs the same amount, then the expense of the land for the new landfill isn't a reason to not choose it.

In this “explain the paradox” question, you are told that for albatrosses, placing geolocation tags in the middle of the back of the bird interferes less with bird movement than does placing geolocation tags under the tail feathers. However most studies on birds in general show the opposite to be true. In looking to resolve this paradox, you should ask yourself - what makes albatrosses and soaring birds special compared to other birds studied?

Choice "Albatrosses are much larger than other soaring birds, so geolocation tags make up less of their total body weight." makes a distinction between albatrosses and other soaring birds. Since both albatrosses and soaring birds are addressed together, this doesn’t given information as to why these birds are more affected by one geolocation tag placement and other birds are more affected by another. Eliminate "Albatrosses are much larger than other soaring birds, so geolocation tags make up less of their total body weight.".

Choice "Geolocation tagging practices have changed over time to include smaller devices." can be eliminated because it deals with change over time - something that isn’t addressed within the question. All the studies referenced could have been in the last year or they could have been over the course of 20 years. There’s no way of knowing, so there’s no way of knowing whether this would have an affect on placement.

If choice "Soaring doesn’t involve the tailfeathers, so geotag placement there will not affect movement." was true, then soaring birds would be less affected by placing the geolocation tags than would other flying birds, not more.

Choice "Albatrosses tend to expend less energy than other birds while soaring because of their large wingspan." can also be eliminated. The question deals with relative interference with movement, not the absolute amount of energy expended.

Choice "The majority of studies were done on penguins, which don’t fly but do spend much of their time hunting underwater." is correct. You are told that geolocation tags can affect drag (which occurs in the water) and lift (which occurs in the air). Since you are told that penguins can’t fly but that they do swim, you can conclude that only drag matters, so if the majority of studies were done on penguins, then the majority of studies would say that the ideal placement is under the tailfeathers.

For Explain the Paradox questions, remember that you need to find an answer that bridges the gap between two seemingly contradictory facts by explaining why both can be true. Don't worry about anticipating the correct answer if you don't automatically see it - just look for the gap that needs to be bridged and find an answer choice that does so.

The argument states that even though more Gala apples are produced than any other apple, more Granny Smith apple trees are sold each year. You are looking for an answer that would result in more Granny Smith trees being sold but still ensure that production of Gala apples was greater than that of any other tree. The only answer that allows for this is "Gala apple stems are often “grafted” onto Granny Smith tree trunks after purchase so that the trees produce Gala apples rather than Granny Smith ones.". If Gala tree stems are grafted onto Granny Smith trunks, so that the trees produce Gala apples rather than Granny Smith ones, that means that at least some of the Granny Smith trees being sold are actually used to produce Gala apples. Choice "Gala apple stems are often “grafted” onto Granny Smith tree trunks after purchase so that the trees produce Gala apples rather than Granny Smith ones." is correct.

Among the other answers, choice "Many Granny Smith apples are produced for decorative rather than culinary purposes, especially in the northeastern United States." can be eliminated because the use of the apple isn't important, just whether or not it's produced. Choices "Many Gala apple trees die before they reach apple producing maturity because their stems are not as hardy as those of Granny Smith apple trees." and "Because the varieties are so similar, many nurseries list sales of both Gala and Pink Lady apple trees as Gala apple tree sales." would actually go counter to what you are trying to accomplish. If "Many Gala apple trees die before they reach apple producing maturity because their stems are not as hardy as those of Granny Smith apple trees." is true, then in order to produce enough apples farmers would have to purchase more Gala trees rather than fewer. Similarly, if "Because the varieties are so similar, many nurseries list sales of both Gala and Pink Lady apple trees as Gala apple tree sales." is true then that means that the number of Gala trees sold is actually underreported, creating a larger contradiction than was previously indicated. Choice "There is no difference between the average spoilage time of an apple coming from a Gala tree and one coming from a Granny Smith tree." can also be eliminated. Spoilage time can only affect the number of apples sold (since some will not make it to market) NOT the number of apples produced, which is what the question is looking for.

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.

While 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.

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. Similarly 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.

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.

In any Plan/Strategy question, it is important to determine exactly what the goal of the plan is. Here the goal is to "substantially reduce marijuana use," which you should see is different from related goals (perhaps to reduce marijuana sales or to eliminate marijuana use). Precision in wording and understanding the exact goal are keys to these questions.

You can anticipate reasons that raising the sales tax and therefore the cost of marijuana might not result in a significant decrease in marijuana use. Focusing on use - and not sales - provides a great entry point: what if people find a way to get marijuana without having to buy it? Choice "The state law that legalized marijuana also allows residents to grow a small amount of marijuana for personal use.​" suggests that they might be able to simply grow it on their own and avoid both the price and the tax.

What if they can buy it somewhere else and avoid the tax? That leads to answer choices:

"Despite the legalization of marijuana, there remains a non-trivial black market for the illegal sale of marijuana in Kerry County.": If people can buy it on the black market and avoid paying the sales tax, then they can still use it without being affected by the tax.

"Kerry County is among the smallest counties in the state, with no location that is more than a 20-minute drive from a neighboring county.": If people can buy it nearby in a county that doesn't have the tax, then they'll avoid the tax.

What if the tax just isn't that big of a deterrent? Choice "Marijuana use has been most popular among young professionals, a demographic that tends to have a large amount of disposable income." suggests that the largest group of users may must not care about paying more to use marijuana.

That leaves choice "Kerry County already levies similar "sin tax" sales taxes on other recreational drugs such as alcohol and tobacco.", which you should see does not directly address marijuana at all. Even if similar taxes for similar goods are already on the books, that still means that the net cost of marijuana will markedly increase under the sales tax. If that is, indeed, a deterrent then the taxes on similar goods won't matter. "Kerry County already levies similar "sin tax" sales taxes on other recreational drugs such as alcohol and tobacco." does not attack the problem head on, and is therefore the only answer choice that does not give reason to believe that the plan will not work.