Public health official: Some researchers suspect that magnetic fields from high-voltage power lines can cause health problems for people who...
GMAT Critical Reasoning : (CR) Questions
Public health official: Some researchers suspect that magnetic fields from high-voltage power lines can cause health problems for people who live especially near the lines. However, this is extremely unlikely: Beyond a distance of a few feet, the strength of the magnetic fields from high-voltage power lines is less than the average strength of magnetic fields in homes that are not located near such lines.
Which of the following would it be most useful to establish in order to evaluate the public health official's argument?
Passage Analysis:
| Text from Passage | Analysis |
| Some researchers suspect that magnetic fields from high-voltage power lines can cause health problems for people who live especially near the lines. |
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| However, this is extremely unlikely: |
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| Beyond a distance of a few feet, the strength of the magnetic fields from high-voltage power lines is less than the average strength of magnetic fields in homes that are not located near such lines. |
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Argument Flow:
The official presents a concern (researchers think power lines cause health problems), then immediately dismisses it with a conclusion (this is extremely unlikely), and finally provides supporting evidence (power lines have weaker magnetic fields than homes once you're a few feet away).
Main Conclusion:
It's extremely unlikely that magnetic fields from power lines cause health problems for people living near them.
Logical Structure:
The argument uses comparative evidence to support the conclusion. Since power lines produce weaker magnetic fields than regular homes (at distances beyond a few feet), and we don't see widespread health problems from home magnetic fields, the official concludes power lines shouldn't cause health problems either.
Prethinking:
Question type:
Evaluate - We need to think of assumptions the argument makes and create scenarios that would either strengthen or weaken the conclusion when taken to extremes
Precision of Claims
The argument makes specific quantitative claims about magnetic field strength (beyond a few feet, power lines are weaker than average home fields) and a quality claim about health effects being extremely unlikely
Strategy
The official concludes health problems are extremely unlikely because power line magnetic fields beyond a few feet are weaker than average home fields. To evaluate this, we need to identify what assumptions this comparison relies on. The key assumption is that if power line fields are weaker than home fields, then they can't cause health problems. We should think of scenarios that would make this comparison either more or less meaningful for determining health risks
This directly addresses the core assumption in the official's argument. The official reasons that power line magnetic fields can't cause health problems because they're weaker than home magnetic fields. But this comparison is only meaningful if we know whether home magnetic fields cause health problems. If home fields DO cause health problems, then even weaker power line fields might still be harmful, undermining the official's conclusion. If home fields DON'T cause health problems, then the official's reasoning is strengthened. This information is essential to evaluate the argument's logic.
The proportion of people who believe power lines cause health problems is irrelevant to evaluating the scientific validity of the official's argument. Public opinion doesn't determine whether the magnetic field strength comparison is a sound basis for concluding health problems are unlikely. The argument relies on physical evidence about magnetic field strength, not public perception.
Whether power lines are routed near residential areas in urban settings doesn't help evaluate the official's reasoning about magnetic field strength. The official's argument is based on a comparison of magnetic field strengths, not on where power lines are located or how many people are affected.
Knowing specific diseases suspected by researchers doesn't help evaluate whether the official's magnetic field strength comparison is valid. The official's conclusion that health problems are extremely unlikely is based on comparative magnetic field strength, regardless of what specific conditions researchers suspect.
Information about workplace magnetic field strength is irrelevant to the official's argument, which compares power line fields to home magnetic fields. Adding workplace data doesn't address whether the home-to-power-line comparison is meaningful for assessing health risks.