GMAT Quiz: Identify Necessary Assumptions

What this quiz covers

This quiz focuses on Identify Necessary Assumptions, giving you a quick way to practice the rules, question types, and explanations that matter most for GMAT.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Employees who telecommute at least twice weekly would otherwise have commuted to their offices during rush hour rather than outside peak times. (correct answer)
2. Telecommuters use less gasoline on the days they work from home than on the days they commute to the office.
3. Most companies in Metroville already have the technological infrastructure to support their employees' working from home.
4. The total number of people commuting into Metroville by car has remained stable over the past five years.

Explanation: When you encounter assumption questions on the GMAT, you need to identify what unstated premise must be true for the argument to work. The conclusion here is that increasing telecommuting would "significantly reduce overall traffic congestion during rush hour." The correct answer is (A) because the director's conclusion specifically targets rush hour congestion. If telecommuters would have normally commuted outside of peak times anyway, then having them work from home wouldn't reduce rush hour traffic at all. The argument depends on the assumption that these workers would otherwise be contributing to rush hour congestion. Let's examine why the other choices don't work: (B) focuses on gasoline usage, which is irrelevant to the conclusion about traffic congestion levels. Even if telecommuters used the same amount of gas, reducing their presence on roads during rush hour would still decrease congestion. (C) addresses implementation feasibility, but the director's argument is about whether telecommuting would reduce congestion if implemented—the availability of infrastructure doesn't affect this logical connection. (D) discusses historical commuting trends, but the argument is forward-looking and doesn't depend on past stability. To master assumption questions, use the "negation test": if you negate the correct assumption, it should destroy the argument. If we negate (A)—assume telecommuters would have commuted outside rush hour anyway—then increasing telecommuting wouldn't reduce rush hour congestion, which completely undermines the director's conclusion. When other answer choices are negated, the argument can still stand.

Question 2

1. Customers who prefer caffeinated coffee will continue to purchase the chain's existing blends in the same quantities as before.
2. The price of the new decaffeinated blend will not exceed that of comparable beverages offered by competitors in the area.
3. The ingredients needed for the new decaffeinated blend can be obtained without disrupting supply of the existing blends.
4. People who currently avoid coffee because of its caffeine content are willing to try a decaffeinated blend rather than choose non-coffee beverages they already purchase. (correct answer)

Explanation: When tackling assumption questions on the GMAT, you need to identify what unstated belief must be true for the argument to work. The managers conclude that a new decaffeinated blend will boost total coffee sales by attracting caffeine-avoiders. The correct answer is D because it identifies the critical gap in this reasoning. The managers assume that people who currently avoid coffee due to caffeine will actually be willing to try their decaffeinated option. Without this assumption, their entire plan falls apart—if caffeine-avoiders simply aren't interested in coffee at all (even decaffeinated), then the new blend won't attract any new customers. Here's why the other choices miss the mark: Choice A addresses whether existing customers will maintain their purchasing habits, but this isn't necessary for the conclusion. Even if some current customers switch to decaf, total sales could still increase if enough new customers are attracted. Choice B focuses on competitive pricing, but the argument doesn't depend on price comparisons—it's specifically about attracting people who avoid coffee due to caffeine, regardless of price. Choice C deals with supply chain logistics, which is operationally important but irrelevant to whether the strategy will actually boost sales. For assumption questions, use the negation test: if you negate the correct assumption, it should destroy the argument. If people who avoid coffee due to caffeine are not willing to try decaf, then the managers' plan cannot succeed.

Question 3

1. Patrons who borrow many items typically require more time at a self-checkout machine than at a staffed desk.
2. Most patrons with only a few items will prefer self-checkout to waiting in line for a staff member. (correct answer)
3. Library staff currently assigned to checkout desks will remain available to assist patrons who experience problems at the self-checkout machines.
4. The new self-checkout machines will be placed where they are visible to patrons as they enter the library.

Explanation: When you encounter assumption questions on the GMAT, you're looking for an unstated premise that must be true for the argument to work. The director's logic is: self-checkout machines → patrons with few items use them → reduced wait times for everyone. The correct answer is B because the director's entire plan depends on patrons with few items actually choosing to use the self-checkout machines. If these patrons don't prefer self-checkout and continue waiting in the regular line, then the wait time problem persists unchanged. The argument assumes behavioral change will occur. Let's examine why the other choices aren't necessary assumptions: A is incorrect because the director's argument doesn't require self-checkout to be faster for people with many items. The plan specifically targets patrons with few items using self-checkout, creating separate lines based on volume. C is incorrect because staff availability for troubleshooting, while potentially helpful, isn't essential to the core argument about reducing wait times through line separation. The argument could work even without dedicated staff support. D is incorrect because machine visibility, though practically useful, isn't a logical requirement of the argument. The director's reasoning about wait time reduction doesn't depend on placement or visibility. Remember this pattern: assumption questions often hinge on whether people will actually behave as the argument expects them to. Look for gaps between "if we build it" and "they will come" - the missing link is frequently about human behavior and preferences.

Question 4

1. shoppers who currently use single-use plastic bags would not start discarding other kinds of plastic packaging at higher rates once the ban is in place (correct answer)
2. the production of reusable cloth bags generates less total waste than does the production of single-use plastic bags
3. most grocery stores already give customers the option of purchasing multi-use plastic containers for bulk items
4. the local landfill currently separates recyclable materials from non-recyclable materials before burial

Explanation: When you encounter GMAT assumption questions, you're looking for a necessary condition—something that must be true for the argument to work. The argument here claims that banning plastic bags will substantially reduce plastic in landfills. The correct answer is A because it identifies a critical gap in the reasoning. The argument assumes people won't simply substitute other plastic waste when bags are banned. If shoppers started throwing away more plastic containers, packaging, or other plastic items after the ban, the total plastic reduction could be minimal or nonexistent. This assumption is necessary—without it, the conclusion falls apart. Let's examine why the other choices fail: B discusses production waste rather than landfill waste, which is irrelevant to the argument's focus on what ends up in local landfills. C about bulk containers is also irrelevant—the availability of multi-use containers doesn't affect whether banning single-use bags reduces landfill plastic. D addresses landfill operations, but whether materials are separated before burial doesn't impact the total amount of plastic entering the landfill, which is what the argument concerns. Notice how A directly challenges the core logic: will the ban actually reduce total plastic waste, or will people just dispose of different plastic items instead? This behavioral assumption is essential to the argument's success. Strategy tip: On assumption questions, look for gaps between the evidence and conclusion. The correct answer often addresses potential alternative explanations or unintended consequences that could undermine the argument's logic.

Question 5

1. Prospective students who would be rejected under the higher standards would still have chosen Northton College if admitted.
2. Alumni base their donation decisions, at least in part, on perceptions of the college's academic rigor. (correct answer)
3. Other institutions in the region are not simultaneously raising their admission standards.
4. The college's endowment managers will invest any additional donations in a diversified portfolio that outperforms inflation.

Explanation: This question tests your ability to identify necessary assumptions in a logical argument. When analyzing any plan or strategy, you need to find what must be true for the plan to work as intended. The board's reasoning follows this chain: raise admission standards → improve academic reputation → attract more alumni donations. For this plan to succeed, there must be a connection between academic reputation and alumni giving behavior. Choice B is correct because it establishes the crucial link in the board's logic. If alumni don't base donation decisions on their perceptions of academic rigor, then improving the college's academic reputation (even if successful) won't lead to increased donations. This assumption is absolutely necessary for the plan to work. Choice A is incorrect because it addresses student choice behavior, which isn't relevant to whether the plan will increase alumni donations. Whether rejected students would have chosen Northton doesn't affect the reputation-donation connection. Choice C is wrong because other institutions' actions don't determine whether Northton's plan will work. Even if competitors also raise standards, Northton could still improve its reputation and attract more donations relative to its current baseline. Choice D focuses on investment strategy for donations that haven't been received yet. How the college manages future donations is irrelevant to whether the plan will actually generate those donations in the first place. Remember: when you see "must be true for the plan to be effective," look for the assumption that bridges the logical gap in the argument. Identify what the plan assumes about cause and effect.

Question 6

1. The students will not compensate for the reduced sodium at school by consuming more high-sodium foods outside school. (correct answer)
2. Potassium-based salt substitutes taste similar enough to regular salt that students will not reject the cafeteria food.
3. High blood pressure in children is primarily caused by excessive dietary sodium rather than by genetic factors.
4. School cafeterias can afford the higher cost of potassium-based salt substitutes without increasing meal prices.

Explanation: Assumption questions test your ability to identify unstated premises that an argument requires to be valid. When an author makes a claim, they often rely on hidden assumptions—if these assumptions are false, the entire argument falls apart. The researcher's argument follows this logic: replacing regular salt with potassium-based substitutes in school cafeterias → lower average blood pressure in students. For this causal relationship to work, the researcher must assume that students won't undermine the intervention through their behavior outside school. If students compensate by eating extra high-sodium foods at home or elsewhere, the salt reduction at school becomes meaningless, and blood pressure won't decrease as predicted. Choice A correctly identifies this critical assumption. Choice B addresses taste and food acceptance, but even if students dislike the substitute, this doesn't break the core argument—it just affects implementation. Choice C focuses on the cause of high blood pressure, but the researcher's claim works regardless of whether sodium is the primary cause; even a secondary factor could still lower average blood pressure when reduced. Choice D concerns cost considerations, which are irrelevant to whether the intervention will actually achieve the claimed health outcome. The key insight is that assumption questions often hinge on potential ways the proposed solution could be undermined or rendered ineffective. Look for answer choices that identify gaps where outside factors could sabotage the argument's conclusion. If you can imagine saying "But what if..." about an assumption, and that scenario would destroy the argument, you've likely found the right answer.

Question 7

1. participants will practice the mindfulness techniques outside the course sessions and not just during class
2. reductions in stress achieved through mindfulness are substantial enough to improve concentration noticeably (correct answer)
3. employers will recognize and reward any productivity gains achieved by course participants
4. participants who enroll in the course currently experience levels of stress that hinder their workplace concentration

Explanation: When analyzing argument assumptions on the GMAT, you're looking for unstated premises that must be true for the conclusion to logically follow. The clinic's argument flows: mindfulness reduces stress → lower stress improves concentration → participants become more productive. The correct answer is B because this assumption is essential for the argument's logic. The clinic claims that mindfulness will increase productivity through stress reduction and improved concentration. However, the argument never establishes that the stress reduction achieved through mindfulness will be meaningful enough to actually improve concentration. If mindfulness only reduces stress by tiny, imperceptible amounts, then the promised productivity gains wouldn't materialize. For the argument to work, the stress reduction must be substantial enough to create noticeable concentration improvements. Choice A is incorrect because the argument doesn't require practice outside class—even if participants only practiced during sessions, the stress reduction and productivity benefits could still occur. Choice C fails because the argument is about whether participants will actually become more productive, not whether employers will notice or reward it. Choice D is wrong because the argument doesn't assume participants currently have stress problems—the course could work even for people with normal stress levels by reducing them further. Remember that assumption questions require you to identify what must be true for the argument to work, not what would strengthen it or what seems plausible. Look for gaps between the premises and conclusion—here, the gap was whether mindfulness creates sufficient stress reduction to meaningfully impact concentration.

Question 8

1. Most current readers of the print edition have reliable Internet access and will continue reading the magazine online. (correct answer)
2. Advertising revenue from an online edition will be sufficient to cover the magazine's production costs.
3. Readers under age thirty constitute the largest untapped market segment for the magazine's content.
4. Competing magazines aimed at younger readers have not already saturated the online space into which the publication hopes to expand.

Explanation: When you encounter assumption questions on GMAT Verbal, you're looking for unstated premises that must be true for the argument to work. The editor's logic flows from "readers under 30 prefer digital" to "moving online will widen readership" – but there's a crucial gap here. The editor assumes that gaining younger readers will result in a net increase in total readership. For this to happen, the magazine can't lose more current readers than it gains from the under-30 demographic. This makes choice A essential: if current print readers don't have reliable internet access or won't transition online, the magazine could actually lose readership despite attracting younger readers. Choice B addresses financial viability, but the argument is specifically about widening readership, not profitability. The editor's conclusion could be correct even if the venture isn't financially sustainable. Choice C suggests under-30 readers are the largest untapped segment, but the argument only requires that this group be large enough to increase total readership – they don't need to be the biggest available market. Choice D concerns market saturation, but even in a crowded online space, the magazine could still attract some younger readers. The argument doesn't require dominating this market, just gaining enough readers to achieve growth. Remember: assumption questions ask what must be true, not what would strengthen the argument. Look for gaps between evidence and conclusion, then find the choice that bridges that gap necessarily rather than helpfully.

Question 9

1. The majority of current bus riders travel distances long enough to benefit from express service rather than from frequent local stops.
2. Traffic congestion caused by automobiles will not increase in the lanes freed up by the faster express buses. (correct answer)
3. Bus drivers will adhere strictly to the designated express and local routes once the new system is implemented.
4. Funding for the express bus lanes will not require reducing the overall number of buses in operation.

Explanation: When you encounter assumption questions, you're looking for an unstated premise that must be true for the argument to work. The council member argues that express lanes will reduce commute times for all bus riders because express buses will move faster and free up road space for local buses. The correct answer is B because the argument's logic breaks down if traffic congestion increases in the freed-up lanes. The council member assumes that when express buses move to dedicated lanes, the remaining lanes will actually provide better conditions for local buses. If car traffic immediately fills that space and creates new congestion, local buses won't benefit from any freed-up road space, undermining the claim that all riders will see reduced commute times. Choice A is tempting but incorrect—even if most riders prefer local stops, the argument could still work if express buses free up enough space for local buses to move faster. Choice C misses the point; driver compliance doesn't affect whether the road space logic works. Choice D addresses funding concerns that aren't relevant to the core assumption about traffic flow and road space utilization. The key trap here is confusing what would make the plan effective versus what the argument assumes. While factors like rider preferences (A) or funding (D) might affect the plan's success, they're not necessary assumptions for this specific logical chain about road space and timing. Strategy tip: In assumption questions, use the negation test—if negating an answer choice would destroy the argument, you've found the assumption.

Question 10

1. Programmers will not deliberately introduce new bugs in order to earn additional bonuses for fixing them. (correct answer)
2. The firm can accurately track and attribute each resolved bug to the responsible programmer.
3. Competitor firms that pay fixed salaries will not recruit the small firm's top programmers.
4. Most software bugs are of a type that can be resolved by an individual programmer rather than by a team effort.

Explanation: When you encounter assumption questions on the GMAT, you're looking for unstated premises that must be true for the argument to work. The argument here is that bonuses for bug fixes will improve code quality. The correct answer is A because management's plan contains a fundamental vulnerability: if programmers can create bugs and then get paid to fix them, the incentive system completely backfires. For the bonus system to improve code quality as intended, management must assume programmers won't game the system this way. Without this assumption, the plan could actually worsen code quality while increasing costs. Let's examine why the other choices aren't necessary assumptions. Choice B about accurate tracking is a practical implementation detail, but even with imperfect tracking, the bonus system could still motivate better coding practices and improve overall quality. Choice C about competitor recruitment is irrelevant to whether the bonus system will improve code quality among remaining programmers. Choice D about individual versus team bug resolution doesn't undermine the core logic—even if some bugs require teamwork, programmers could still be motivated to write cleaner initial code to avoid bugs altogether. Notice that choice A represents a classic assumption pattern: it eliminates a way the plan could backfire spectacularly. When evaluating assumptions, always ask yourself: "What could go wrong with this plan?" Often the correct answer will address the most direct way the reasoning could collapse, rather than focusing on minor implementation challenges.

Question 11

1. no other animal species pollinate the affected tree species as effectively as the fruit bats do (correct answer)
2. the disappearance of the fruit bats was not caused by a reduction in the number of the tree species' flowers
3. seed dispersal by birds does not contribute significantly to the regeneration of the affected tree species
4. seedlings of the affected tree species grow at approximately the same rate in all surveyed areas

Explanation: This is a classic critical reasoning question testing your ability to identify necessary assumptions in causal arguments. When researchers conclude that fruit bats are "necessary pollinators" based on fewer seedlings where bats have disappeared, you need to find what assumption makes their logic work. The researchers observe a correlation (fewer bats = fewer seedlings) and conclude causation (bats are necessary for pollination). For this conclusion to hold, they must assume that no other animals can effectively replace the bats' pollinating role. If other creatures could pollinate just as well, then the bats wouldn't be "necessary," and something else must explain the seedling shortage. Choice A captures this essential assumption perfectly. Without assuming that other pollinators are less effective than fruit bats, the researchers can't conclude the bats are necessary. Choice B is tempting but backwards - it suggests the trees' decline caused the bats' disappearance, which would actually weaken rather than support the researchers' conclusion. Choice C confuses pollination with seed dispersal, which are different processes entirely. While seed dispersal affects where seeds end up, pollination determines whether seeds form in the first place. Choice D about seedling growth rates is irrelevant to the pollination argument. On assumption questions, look for what must be true for the conclusion to follow logically. Often the correct answer addresses potential alternative explanations that would undermine the author's reasoning. If you can think "but what if..." about the argument, the assumption likely addresses that gap.

Question 12

1. Differences in inactive ingredients do not affect the way patients absorb the active ingredients. (correct answer)
2. Most physicians prescribe brand-name medications primarily because of marketing by pharmaceutical companies.
3. The cost savings from using generic drugs will encourage insurance companies to expand coverage.
4. Patients are as likely to follow dosage instructions when taking generic medications as when taking brand-name medications.

Explanation: When you encounter assumption questions on the GMAT, you're looking for an unstated premise that must be true for the argument to work. The advocate's reasoning follows this logic: generic drugs have the same active ingredients as brand-name drugs, therefore patients will have identical therapeutic outcomes. The correct answer is A because it identifies a crucial gap in this reasoning. The advocate focuses only on active ingredients being the same, but completely ignores inactive ingredients. If inactive ingredients could affect how the body absorbs or processes the active ingredients, then having identical active ingredients wouldn't guarantee identical outcomes. For the argument to hold, we must assume that these inactive ingredient differences don't matter—which is exactly what choice A states. Choice B is wrong because the advocate's argument isn't about why physicians prescribe certain drugs, but about therapeutic outcomes when patients switch. Choice C incorrectly focuses on insurance coverage, which is irrelevant to whether therapeutic outcomes will be identical. Choice D addresses patient compliance with dosage instructions, but the advocate's argument assumes proper usage in both cases—the claim is that identical active ingredients lead to identical results, not that patient behavior affects outcomes. Remember that assumption questions often test whether you can spot what the author takes for granted. Look for gaps between the evidence presented and the conclusion drawn. Here, the evidence (same active ingredients) doesn't fully support the conclusion (identical outcomes) without assuming that other factors don't interfere.

Question 13

1. People who discover classical music through streaming services are more likely to attend live concerts than are people who discover the music through radio broadcasts. (correct answer)
2. Classical music organizations have not significantly reduced ticket prices during the past decade.
3. The demographic characteristics of classical concert audiences have broadened in tandem with the rise of streaming services.
4. Most people who already attended classical concerts before the rise of streaming services also use those services.

Explanation: When you encounter an assumption question, you're looking for an unstated premise that must be true for the argument to work. The historian argues that streaming services caused increased concert attendance by making orchestral exploration easier. For this causal claim to hold, there must be a meaningful connection between streaming discovery and live attendance. Answer choice A provides this crucial link by assuming that streaming discovery leads to concert attendance more effectively than other discovery methods (like radio). Without this assumption, the historian's argument falls apart—if streaming were no better than existing discovery methods at driving attendance, it couldn't explain the sharp rise in concerts. Here's why the other choices don't work: B focuses on ticket prices, but the historian's argument is specifically about streaming's role in music discovery, not pricing factors. Even if prices dropped, that wouldn't invalidate the streaming explanation. C suggests demographic broadening, which might be a result of the historian's theory but isn't necessary for it to be true—streaming could drive attendance increases within existing demographics. D discusses whether existing concertgoers use streaming, but this is irrelevant since the argument concerns how streaming attracts new attendees, not what current attendees do. Remember that assumption questions require you to identify what the author takes for granted. Look for the missing logical bridge between evidence and conclusion. In causal arguments like this one, the assumption often involves why the proposed cause is more effective than alternatives.

Question 14

1. Consumers will not perceive the price increase as excessive relative to their budgets for confectionery purchases.
2. Competitors will not simultaneously raise the prices of their own premium chocolate bars.
3. Customers who already purchase the chocolate bars will not switch to less expensive alternatives after the price increase. (correct answer)
4. Retail stores will continue to place the premium chocolate bars in the same prominent shelf locations after the price increase.

Explanation: When you encounter assumption questions on the GMAT, you're looking for an unstated premise that must be true for the argument to work. If the assumption is false, the argument falls apart. The analyst argues that raising prices will increase sales volume because customers judge quality by price. For this logic to hold, the analyst must assume that current customers won't abandon the product due to the higher price. If existing customers switch to cheaper alternatives after the price increase, then sales volume would decrease, directly contradicting the predicted outcome. Choice C captures this essential assumption – without it, the argument's conclusion becomes impossible. Let's examine why the other choices aren't necessary assumptions. Choice A addresses whether customers perceive the increase as excessive, but the argument could still work even if some customers find it expensive, as long as the quality perception boost outweighs this concern. Choice B about competitor pricing isn't required – the argument could succeed regardless of what competitors do, since it's based on customers' quality perceptions of this specific product. Choice D concerning shelf placement is irrelevant to the core argument about price-quality perception; the reasoning doesn't depend on product positioning. Strategy tip: For assumption questions, use the "negation test" – if negating an answer choice destroys the argument's conclusion, you've found the correct assumption. Negating C (customers will switch to cheaper alternatives) would make increased sales volume impossible, confirming it's the right answer.

Question 15

1. students will use the laptops primarily for educational purposes rather than for entertainment
2. the schools' Internet infrastructure can handle the increased traffic generated by widespread laptop use
3. online educational resources are more effective at improving test scores than are traditional textbooks alone (correct answer)
4. teachers will integrate the laptops into their lesson plans in a way that complements existing instructional methods

Explanation: When you encounter assumption questions on the GMAT, you're looking for unstated premises that must be true for the argument to work. The consultant's logic flows: free laptops → easier access to online resources → improved test scores. This chain has a critical gap. The correct answer is C because the argument fundamentally assumes that online educational resources actually improve test scores better than what students currently have. Without this assumption, the entire argument collapses. If online resources were no more effective than traditional textbooks, then providing laptop access wouldn't logically lead to score improvements. The consultant presents this effectiveness as a given, but it's actually an unstated assumption the argument requires. Looking at the wrong answers: A assumes students must use laptops educationally, but even if some students use them for entertainment, others using them educationally could still improve scores overall. B addresses technical infrastructure, which could be a practical concern but isn't logically necessary for the argument—the consultant could assume adequate infrastructure exists. D focuses on teacher integration, but students could independently access online resources and improve scores without specific teacher-led integration. Remember that assumption questions ask what must be true, not what would be helpful or ideal. The key strategy is to identify the logical gap between premises and conclusion. Here, the gap is whether online resources are actually superior to existing educational materials—without this assumption, there's no reason to expect the promised improvement.

Question 16

1. Diners who see calorie information will choose lower-calorie options in sufficient numbers to affect average caloric intake. (correct answer)
2. Restaurants will not compensate for potentially lower sales of high-calorie dishes by increasing portion sizes of lower-calorie items.
3. Individuals tend to eat out at restaurants more often than they prepare meals at home.
4. Obesity is caused primarily by excessive caloric intake rather than by lack of physical activity.

Explanation: When you encounter GMAT assumption questions, you're looking for a statement that must be true for the argument to work. The argument here creates a logical chain: calorie labeling → fewer calories consumed → reduced obesity rates. The correct answer is A because it identifies the critical gap in this reasoning. The official assumes that simply providing calorie information will actually change dining behavior in meaningful ways. Without this behavioral change happening "in sufficient numbers to affect average caloric intake," the entire argument collapses. If diners largely ignore the calorie counts or if only a tiny fraction change their choices, then average consumption won't decrease and obesity rates won't improve. Looking at the wrong answers: B addresses a potential problem but isn't necessary for the basic argument to work - even if some restaurants increase portions, the argument could still succeed if enough diners choose lower-calorie options overall. C is irrelevant because the argument only claims that mandating calorie counts will help when people do eat out - it doesn't require that restaurant dining be more frequent than home cooking. D, while potentially true, isn't required for this specific argument since the official's claim is limited to the relationship between calorie labeling and consumption, not about obesity's primary causes. Strategy tip: In assumption questions, ask yourself "What if this weren't true?" If negating a statement destroys the argument, you've found your assumption. Here, if diners don't actually change their behavior based on calorie information, the official's entire plan fails.

Question 17

1. adding international stocks does not increase exposure to currency-exchange risk enough to offset the benefits of diversification (correct answer)
2. countries with historically high returns will continue to outperform domestic markets in the future
3. transaction costs for purchasing international stocks remain negligible relative to expected returns
4. most investors' existing portfolios lack adequate representation of international equities

Explanation: When you encounter assumption questions in GMAT Critical Reasoning, you're looking for an unstated premise that the argument requires to be true. The adviser claims that adding international stocks will "always" lower portfolio risk due to imperfect correlation between countries' returns. The adviser's reasoning has a gap: while diversification through uncorrelated assets does reduce some risks, international investing introduces new risks, particularly currency exchange risk. When you invest internationally, currency fluctuations can significantly impact your returns regardless of how the underlying stocks perform. For the adviser's claim that international diversification "always" reduces risk to hold true, the benefits of diversification must outweigh any additional risks introduced. Choice A correctly identifies this assumption. The adviser must assume that currency exchange risk doesn't increase portfolio risk enough to cancel out diversification benefits. Choice B is incorrect because the argument isn't about future performance superiority—it's about risk reduction through diversification. Choice C misses the mark because transaction costs, while relevant to profitability, don't address the core claim about risk reduction. Choice D assumes something about investors' current holdings that the adviser never suggests; the argument would work regardless of existing portfolio composition. Remember that assumption questions often involve identifying what must be true for an argument's logic to work, especially when the conclusion seems overly broad. Look for gaps between the evidence presented and the strength of the conclusion—words like "always" should make you particularly alert to unstated conditions.

Question 18

1. LED lamps provide illumination levels at least equal to those provided by the conventional streetlights being replaced. (correct answer)
2. Maintenance costs for LED lamps will not exceed the savings generated by lower electricity usage.
3. Residents will not increase their private outdoor lighting to compensate for any perceived reduction in streetlight brightness.
4. Electricity rates charged to the city will remain constant after the conversion to LED technology.

Explanation: When you encounter assumption questions on the GMAT, you're looking for a statement that must be true for the argument to work. The utility company argues that LED streetlights will cut electricity consumption by 50% "without compromising public safety." This safety claim is crucial to the argument's logic. The correct answer is A because the utility's claim inherently assumes that LED lamps maintain adequate illumination for public safety. If LED lamps provided significantly less light than conventional streetlights, public safety would indeed be compromised, making the entire claim false. The company cannot simultaneously promise both energy savings and uncompromised safety unless the LED technology maintains at least equivalent lighting levels. Let's examine why the other options aren't necessary assumptions: B addresses maintenance costs, but the argument only claims reduced electricity consumption—it doesn't promise overall cost savings, so maintenance costs are irrelevant to this specific claim. C suggests residents might add private lighting, but even if they did, this wouldn't affect the city's streetlight electricity consumption, which is what the utility specifically measured. D focuses on electricity rates remaining constant, but even if rates changed, the 50% reduction in consumption would still occur—the utility could still deliver on its promise of cutting the city's streetlight electricity usage by half. Strategy tip: In assumption questions, focus on gaps between the evidence and conclusion. Here, the gap was between "energy reduction" and "no safety compromise"—the missing link was equivalent illumination levels.

Question 19

1. The additional protein and reduced carbohydrates are not offset by higher levels of unhealthy fats or calories in almond flour. (correct answer)
2. Consumers will find the taste and texture of almond-flour cookies at least as appealing as those of wheat-flour cookies.
3. People with nut allergies constitute a small percentage of potential cookie consumers.
4. The cost of almond flour will decrease as demand for it increases.

Explanation: Questions asking what an argument "presupposes" are testing your ability to identify unstated assumptions—the missing logical links that must be true for the argument to work. Think of assumptions as the invisible foundation supporting the argument's conclusion. The scientist concludes that almond flour makes cookies "healthier" based solely on higher protein and lower carbohydrates. But for this reasoning to be valid, the scientist must assume that these benefits aren't undermined by other nutritional factors. If almond flour contained dramatically more unhealthy fats or calories, the cookies might actually be less healthy overall despite the protein and carbohydrate advantages. Choice (A) captures this essential assumption—that the stated benefits aren't offset by hidden drawbacks. Choice (B) addresses consumer preference, but the scientist's argument is about health benefits, not taste appeal. Whether people like the cookies doesn't affect whether they're actually healthier. Choice (C) focuses on nut allergies, which is irrelevant to the core health argument—the scientist isn't claiming the cookies are safer for everyone, just healthier in general. Choice (D) discusses cost, but economic factors don't impact the nutritional comparison the scientist is making. When tackling assumption questions, use the "negation test": if you negate the correct assumption, it should destroy the argument. If almond flour's benefits were offset by unhealthy fats or excess calories, the scientist's health claim would collapse. Always look for the assumption that, if removed, would make the entire argument fall apart.

Question 20

1. Visitors who cannot find seating often finish food or beverages while walking and subsequently drop trash along pathways. (correct answer)
2. The additional benches will not obstruct maintenance vehicles or emergency access routes within the park.
3. Installing benches is less expensive than increasing the number of trash receptacles in the park.
4. Park regulations against littering are already clearly posted yet are insufficient on their own to deter littering.

Explanation: When you encounter assumption questions on the GMAT, you're looking for an unstated premise that must be true for the argument to work. The argument here connects comfortable seating to reduced littering, so you need to identify what logical gap the director's reasoning depends on. The director's claim creates a logical chain: more benches → comfortable seating → less littering. But there's a missing link between having nowhere to sit and the actual act of littering. For this argument to hold, there must be some connection between lack of seating and littering behavior. Choice A provides exactly this missing link. It assumes that visitors without seating consume food and drinks while walking, then drop trash along pathways. This assumption is essential because it explains why lack of seating would lead to littering in the first place. Without this connection, the director's solution doesn't address the actual cause of the problem. Choice B addresses practical implementation concerns but isn't necessary for the logical validity of the claim itself. Choice C makes a cost comparison that's irrelevant to whether benches will reduce littering. Choice D discusses existing regulations, but the director's argument doesn't depend on the effectiveness or visibility of current anti-littering measures. The key strategy for assumption questions is to identify what unstated premise bridges the gap between evidence and conclusion. Look for the answer that, if removed, would make the argument fall apart completely. Here, without the assumption that people without seats litter while walking, the entire bench solution becomes illogical.