GMAT® Strengthen, Weaken, and Assumption Questions: A Complete Guide
If you've spent any time with Critical Reasoning, you've probably noticed that assumption, strengthen, and weaken questions get taught as three separate subjects. The question stems read differently, and most prep books give each type its own chapter, so it makes sense to treat them as three strategies to memorize. They work as one system on the GMAT®, though. All three turn on the same kind of unstated claim, the assumption that connects an argument's evidence to its conclusion, and one reading method sets up all three, though each stem asks you to do something different with what you find.
This guide covers where these questions sit on the exam, the method they share, what each type asks you to do, a worked example, and how to study the group.
Where these questions sit
The Verbal section has 23 questions in 45 minutes, split between Critical Reasoning and Reading Comprehension. Expect somewhere around 10 to 13 Critical Reasoning questions, with the adaptive algorithm deciding the exact mix on every test. Within Critical Reasoning, strengthen and weaken questions typically show up more than any other single type, so these questions deserve the largest share of your Critical Reasoning practice.
Each Critical Reasoning question follows the same format: a short argument on top, a question stem underneath, and five answer choices. One question per argument, and the stem changes what you're asked to do with the paragraph above it. That's why we recommend reading the stem first: it tells you your job before you read the argument.
The shared core: conclusion, evidence, and the assumption
Arguments in this group have the same three working parts. The conclusion is the author's ultimate opinion, the claim the rest of the argument supports. The evidence is whatever the author offers for it: facts, data, or the stated opinions of other people. The assumption is the claim the author never wrote down but that has to be true, or the evidence stops supporting the conclusion.
A small example shows the distinction. Say a café owner notices that sales rose 10 percent in the months after she started opening an hour earlier, and she concludes that the earlier opening brought in new customers. The evidence is the sales increase. The conclusion is her opinion about what caused it. The assumption is the part she never proved: that the increase came from the earlier opening rather than from something else that changed at the same time, like a new apartment building next door.
That third part never appears on the screen. No answer choice names it, and the argument doesn't state it. The gap between the evidence and the conclusion is usually where you find it. On these three types, finding it is most of the work, and the stem only changes what you do with it once you have it.
Assumption questions
An assumption question hands you a complete argument and asks what it depends on. A typical stem reads, "The argument depends on which of the following assumptions?" The wording varies, but the task doesn't. An answer qualifies as the assumption when it meets two conditions: it isn't stated anywhere in the argument, and it must be true for the conclusion to hold.
The method: find the conclusion, find the evidence, then ask what has to be true for this evidence to support this conclusion. Draft the assumption in your own words before you look at the choices. Drafting the assumption first matters because assumption answer choices are written to sound reasonable whether or not the argument needs them.
One check helps when two choices both look plausible. Take the choice you're considering, imagine it's false, and ask whether the conclusion can still stand. If the argument survives without it, the argument doesn't depend on it.
Wrong answers tend to be one of two things: a restatement of evidence that's already written down, or a new claim the conclusion doesn't need. Both sound helpful. Neither is required, which is why an answer that merely helps can look right and still be wrong.
Strengthen and weaken questions
Strengthen and weaken questions ask you to add something to the argument. The answer choices contain new information the argument didn't mention, and your job is to judge what that new information does to the conclusion. A strengthen answer makes the conclusion more likely to be true. A weaken answer makes it less likely.
The connection usually runs through the assumption. When a new fact makes the assumption more likely to be true, the conclusion it supports becomes more likely too, and that's a strengthen answer. When a new fact makes the assumption less likely to be true, the conclusion becomes less likely too, and that's a weaken answer. This is why the same first read serves all three types: conclusion, evidence, assumption, and only then the answer choices.
A correct strengthen answer rarely proves the conclusion, and a correct weaken answer rarely destroys it. If the café owner's assumption is that the earlier opening explains her sales increase, an answer stating that the apartment building next door opened two years ago makes her assumption more likely to be true without proving it. Reading every choice as proof or refutation can lead you to eliminate a correct answer that only moves the likelihood somewhat.
Questions that ask you to fill in a blank in the argument are usually strengthen questions. If the blank sits at the end and the stem says the completed argument would be well supported, you're looking at a strengthen question with a fill-in-the-blank format.
Eliminate in two passes here. Go through all five choices once and remove anything that's clearly wrong, including the long, convoluted ones you'd otherwise spend minutes on. Then spend your remaining time on the two or three survivors. Decoding one confusing choice in depth before checking the obvious eliminations is the slow way through this question type.
Retail sales in Millbrook's downtown district rose 12 percent in the year after the town redesigned the district's streets, adding wider sidewalks and bicycle lanes. The mayor concluded that the redesign caused the increase and proposed similar redesigns for two other districts, predicting similar gains there.
Which of the following, if true, most seriously weakens the mayor's prediction?
(A) The downtown redesign was completed several weeks behind schedule.
(B) Surveys show that visitors to downtown Millbrook appreciate the wider sidewalks.
(C) Most of the increase came from residents of a housing development that opened in the district the same year.
(D) The bicycle lanes are used by an average of forty cyclists per day.
(E) Several nearby towns have also redesigned some of their commercial streets in recent years.
Try this one before reading on.
Worked solution
Start with the conclusion: the mayor predicts that redesigning the two other districts will produce similar gains. The evidence is the 12 percent rise downtown in the year after the redesign. The assumption is the unstated claim in between: that the redesign caused the rise, rather than something else that happened at the same time.
Now read the choices for new information about that assumption. Choice (C) supplies a competing explanation: a housing development opened in the district that year, and residents of that development account for most of the increase. That makes the mayor's assumption less likely to be true, which makes the prediction less likely to hold. It doesn't prove the redesign did nothing, and it doesn't have to. The stem asks for the answer that most seriously weakens the prediction, and (C) weakens it more than any other choice.
The wrong choices each miss the assignment in a different way. (A) is about the construction schedule, which has no connection to what caused the increase. (B) describes how visitors feel about the sidewalks, which doesn't connect the redesign to retail revenue. (D) is a neutral statistic about bicycle use. (E) notes that other towns redesigned streets too, which doesn't explain Millbrook's increase and says little about whether the gains will repeat elsewhere. Every choice here is new information. Only (C) gives you a reason to doubt that the gains will repeat.
How to study this group
Study the three types together, because the test will mix them. Drill each type's job until you can name it without pausing: assumption, the unstated claim the argument depends on; strengthen, new information that makes the conclusion more likely; weaken, new information that makes it less likely. A one-page sheet or flashcards listing the Critical Reasoning subtypes keeps the jobs separate. Then mix the subtypes together so the identifying step gets practice too.
Build accuracy before speed. By test day, you want to find a Critical Reasoning argument's conclusion and evidence in under 90 seconds, and closer to a minute if you can get there, but that pace comes from repetition rather than from rushing early sets. The drill that builds it: take 20 to 50 arguments from the Official Guide, skip the questions, and name the conclusion and the evidence for each. Our Critical Reasoning strategy guide covers this drill in detail.
Use official questions for this group. The stems, the new-information style of the answer choices, and the size of the likelihood shifts follow a consistent style in GMAC's material, and third-party questions can drift from it. When you miss a question, sort it by type in review so you can see whether assumption, strengthen, or weaken questions are costing you points. Our error log guide covers tracking that without the spreadsheet overhead, and our guide to reviewing practice tests covers how deep the review should go.
Frequently asked questions
What's the difference between an assumption question and a strengthen question?
An assumption question asks for the unstated claim the argument depends on, and that claim must be true or the conclusion fails. A strengthen question asks for new information that makes the conclusion more likely, and that information doesn't need to be anything the argument depends on. A strengthen answer just helps. An assumption answer is required.
What are strengthen and weaken questions on the GMAT®?
They're Critical Reasoning questions whose answer choices introduce new information. A strengthen answer makes the argument's conclusion more likely to be true, and a weaken answer makes it less likely. Strengthen and weaken questions typically appear more often than any other Critical Reasoning type.
How many strengthen and weaken questions are on the GMAT® Focus Edition?
The Verbal section has 23 questions, around 10 to 13 of which are Critical Reasoning, and the algorithm controls the exact mix of subtypes on each test. Strengthen and weaken questions typically make up the largest share of those 10 to 13, but the count varies.
Do the right answers prove or disprove the conclusion?
Usually not. A correct strengthen or weaken answer shifts how likely the conclusion is, sometimes by a lot and sometimes by a little, which is why the stems say things like "most seriously weakens."
Should I read the question or the argument first?
Read the question first. The stem gives you the task before you read the argument, and the task changes by type: describing roles, finding an assumption, weakening a conclusion. Our Critical Reasoning strategy guide covers the full process step by step.
What should I do if I can't find the assumption?
Draft it in your own words before reading the choices: ask what has to be true for the evidence to support the conclusion. If the argument is still unclear after that, make a quick guess and move on. The let-go decision applies to question types as well as individual questions, and that time is usually better spent on questions where the structure is clear.
Want to learn even more?
Our podcast covers Critical Reasoning strategy in detail, including the episode "Critical Reasoning: Quiz, Strategies, and Keys to Success," which walks through every Critical Reasoning question type and the method they share. You can listen on Spotify, Apple Podcasts, or YouTube.
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