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Difficulty: MediumStrengthening Arguments

A renewable energy company recently installed ultrasonic anti-scaling transducers along the fluid conduits of its geothermal power plant. Management hypothesized that high-frequency sound waves from these devices would prevent mineral deposits from adhering to the interior of heat exchanger pipes, thereby eliminating the need for periodic chemical cleaning shutdowns. Over the subsequent six-month evaluation period, the plant operated continuously without requiring a single descaling shutdown, and net electricity output remained constant. Management concluded that the ultrasonic transducers were directly responsible for preventing mineral scale accumulation during this period.

Which of the following, if true, most strengthens management's conclusion?

  1. An adjacent geothermal well drawing from the identical fluid reservoir, operating without ultrasonic transducers, experienced severe mineral scaling that required three cleaning shutdowns during the same six-month period.Answer
  2. B
    The geothermal fluid drawn by the plant contained significantly lower concentrations of dissolved calcium and silica over the past six months than in any previous operational period.
  3. C
    Ultrasonic anti-scaling transducers consume significantly less auxiliary power during operation than chemical circulation pumps.
  4. D
    Plant engineers conducted regular inspections of the external pipe housing throughout the test period to check for mechanical wear.
  5. E
    The total financial cost of purchasing the transducers was fully offset by the revenue generated from continuous electricity output during the six months.

Answer

The argument is most strengthened by the finding that an adjacent, identical well lacking transducers suffered severe scaling under the same conditions.
The conclusion asserts a direct cause-and-effect relationship between the installation of ultrasonic transducers and the absence of mineral scale buildup. The option referencing the adjacent well drawing from the same fluid reservoir acts as a controlled experiment. By demonstrating that scaling still occurred in the absence of transducers under identical fluid conditions, it rules out the alternative explanation that fluid composition naturally prevented scaling, thereby strongly supporting the conclusion that the transducers caused the observed result.

Step-by-Step Solution

1
Identify the conclusion and underlying causal logic.
Conclusion: Ultrasonic transducers prevented mineral scale accumulation. Causal premise: Transducers were installed, and no scaling shutdowns occurred for six months.
To strengthen a causal conclusion, one must demonstrate that the cause produced the effect and rule out alternative causes (e.g., natural drop in mineral levels).
2
Evaluate the impact of establishing a comparative control group.
Showing that an identical well without transducers experienced scaling confirms that scaling conditions were present, establishing that the transducers were the critical difference-maker.
A control group isolates the causal variable and confirms that the outcome was not due to ambient environmental changes.

Key Concept

Strengthening Causal Arguments via Controlled Comparison
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Topics

Strengthening Arguments

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