Assumption—#%. The correct answer choice is (D)
This chemical company employee discusses the pollution that is released by 30 small companies. A conservation group’s study showed that the employee’s company and four other small companies account for 60% of the total pollution produced by the 30 companies considered. Based on this percentage, the employee concludes that his or her company releases more pollution that the majority of other similarly-sized companies:
- Premise: Of the 30 small chemical companies studied, the employee’s company, together with four others, produced about 60% of the total.
Conclusion: The employee’s company clearly releases more pollutants that most other companies of the same size.
The sample of small companies is limited (though the author appears to presume that it is generally representative), and the information about the companies’ releasing 60% of the pollution is rather vague (the employee’s company is combined with four others, without any information about the distribution of pollution released by the five companies).
The question that follows the stimulus asks for an assumption that is required of the author’s argument, so the Assumption Negation Technique can be applied to confirm the correct answer choice: The right answer will provide an assumption which, when negated, will hurt the author’s argument.
Answer choice (A): The employee’s argument does not rely upon the assumption presented here; to confirm that this is not a necessary assumption, when we “take away” this assumption, the negated version of this choice is as follows:
The group that produced the study is hostile to the chemical industry.
This in itself would not take away from the credibility of the study, which compares many companies within the chemical industry, nor would it weaken the author’s argument, so this is not an assumption on which the stimulus’ conclusion relies.
Answer choice (B): The emphasis of the study is on the amounts of pollution released by the various companies, with no focus on the specific chemicals being processed. As such, this choice is irrelevant to the issue and cannot be an assumption required by the argument.
Answer choice (C): The study presented in the stimulus limited its focus to the pollution released by 30 small chemical companies, and the author’s conclusion is limited to that discussion as well. The issue of how small companies’ production of pollutants compares with that of big companies is not relevant to the discussion, so this cannot be an assumption that the author’s argument requires.
Answer choice (D): This is the correct answer choice. In drawing the conclusion in the stimulus, the employee must assume that the other four companies did not comprise the vast majority of the referenced 60% of the total pollution. To confirm that this is not an assumption on which the employee’s argument relies, we can take away, or logically negate, the assumption presented, and note the effect on the author’s argument:
The four other companies together do account for close to 60% of the pollution produced by the 30 companies.
If this is the case, then the employee’s company accounts for a very small percentage of the total pollution under consideration. Since the negated version of this choice clearly hurts the employee’s argument, this choice is confirmed as the right answer to this Assumption question.
Answer choice (E): The argument presented by the employee does not rely on assuming no significant variation among the other 25 companies regarding pollution released by each. To confirm that this is not an assumption on which the author relies, the logically negated version is as follows:
There is significant variation in the quantities of pollution released by the other 25 companies.
This choice deals only with the 25 companies other than the five that the employee discusses. Those other 25 companies accounted for the rest of the overall pollution created by all the companies studied, but how much variation there was among those 25 companies is irrelevant. Since the logically negated version of this choice does not hurt the employee’s argument, this is an assumption upon which the employee’s argument relies.