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VerbalCritical Reasoning

Free GMAT Critical Reasoning Practice Question

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Across a region's manufacturers, plants that adopted automation reported higher output per worker than plants that did not. Yet within both the large-plant group and the small-plant group examined separately, automated plants reported lower output per worker than non-automated plants. An analyst concludes that automation lowers output per worker. Which of the following, if true, would most seriously weaken the argument above?

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Answer & Explanation

Correct answer

E

Weaken the conclusion that automation lowers output per worker. The conclusion rests on the within-group finding that, in each size group, automated plants show lower output than non-automated ones. (E) undercuts this by supplying a non-causal source for that gap: the plants that automated were already lower in output before automating, so the gap reflects which plants chose to automate rather than an effect of automation.

(A) supports comparability of the measure. (B) product variety, (C) maintenance downtime, and (D) total headcount give no reason the within-group gap would mislead, so none weakens the causal claim.