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VerbalCritical Reasoning

Free GMAT Critical Reasoning Practice Question

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Verlan Markets, a regional grocery chain, recently installed self-checkout lanes in all of its stores. To assess the change, the company emailed a short satisfaction survey to every one of its 40,000 loyalty-program members. Of the 1,800 members who completed the survey, 72 percent reported that the self-checkout lanes made their shopping trips faster. The chain's operations director concluded from these results that most of Verlan's loyalty members find the self-checkout lanes faster and that the chain should therefore continue expanding them.

The director's reasoning is most vulnerable to criticism on the grounds that it

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Answer & Explanation

Correct answer

B

This is a describe-the-flaw question, so the credited choice names, in general terms, the specific reasoning error the argument actually commits. First isolate the structure. Evidence: of the 1,800 members who completed the survey, 72 percent said the lanes made shopping faster. Conclusion: most of the chain's 40,000 loyalty members find the lanes faster. The leap is from what respondents said to what the whole membership thinks. The 1,800 respondents are only about 4.5 percent of the membership, and they were not chosen at random; they are the people who chose to answer. People who feel strongly, or who are simply more willing to fill out surveys, are over-represented among them. So the 72 percent figure describes the respondents, not the membership, and the argument has no basis for assuming the two groups think alike. That is exactly the defect (B) names: it treats the self-selected respondents as representative of all members.

Why each other choice fails. (A) names a recognizable flaw, distrusting a biased source, but the members are simply reporting their own shopping experience, which is the relevant evidence for a claim about how members perceive the lanes; the argument does not lean on a partial authority. The authoritative phrasing makes it sound like a sharp methodological catch, which is the trap. (C) accuses the argument of equating speed with enjoyment, but enjoyment is never mentioned; the conclusion stays entirely about speed, so this describes a move the argument does not make. (D) is the closest trap: overlooking a factor that affects an outcome is a real flaw type, and it sounds survey-adjacent. But the conclusion is about whether members perceive the lanes as faster, not an objective claim about what causes checkout speed, so how many items a shopper buys does not touch the generalization the argument actually makes. (E) merely restates a feature of the argument: drawing a recommendation about continued expansion from evidence about current satisfaction is an ordinary inference, not a logical error. Because only (B) names the error the argument genuinely commits, (B) is correct.