Public health official: Some researchers suspect that magnetic fields

Question

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?

(A) Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes

(B) What proportion of people who live near high-voltage power lines believe that those lines may cause health problems

(C) Whether high-voltage power lines are routed near residential dwellings in urban areas

(D) What specific diseases or conditions are suspected by some researchers to result from exposure to magnetic fields from high-voltage power lines

(E) What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines

KarishmaB · Accepted Answer

- Magnetic fields from power lines can cause health problems to people living close by.
- Far away homes have stronger magnetic fields (caused by something else at home) than the strength of magnetic field close to power lines.

Conclusion: It is unlikely that magnetic fields from power lines cause health problems to people living close by.

Mind you, we are talking about different kinds of magnetic fields - those generated by power lines and those generated at home by other sources. We are saying that magnetic fields from power lines are weaker in people's homes that are close by. Stronger magnetic fields exist in far away homes. So it is unlikely that magnetic fields from power lines can cause health problems (because they are weaker) and stronger fields already exist.

Which of the following is useful to evaluate:

(A) Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes

We are asking whether the magnetic fields at home are harmful. If they are stronger and harmful like the magnetic fields of power lines, then it is true that weak fields of power lines may not be a source of worry. But say that magnetic fields of home at harmless - then it doesn't matter how strong they are, they will not cause any worries. The weaker fields of power lines may be a source of worry then because even the weak fields may cause health problems. 
Basically, we are trying to find out whether the two types of magnetic fields are comparable. If they are not similar, then the argument may not hold since the argument is based on this comparison.

(B) What proportion of people who live near high-voltage power lines believe that those lines may cause health problems

People's beliefs have nothing to do with what actually happens. Irrelevant.

(C) Whether high-voltage power lines are routed near residential dwellings in urban areas.

Whether residential areas are near power lines is irrelevant. We want to find out what happens when they are close to power lines.
So our argument is what happens when A happens? Whether A actually does happen or not is irrelevant.

(D) What specific diseases or conditions are suspected by some researchers to result from exposure to magnetic fields from high-voltage power lines

The actual diseases are irrelevant. We are talking about all health problems.

(E) What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines

Our argument talks only about homes, not workplaces.

Answer (A)

Marcab · Answer

Point 1: Some researchers suspect that magnetic fields from high-voltage power lines can cause health problems for people who live especially near the lines.
Point 2: Public health official states that this is very unlikely as 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.

We have to evaluate whether it is unlikely that those magnetic lines have a negative effect on health of people.
 Among the available answer choices, A is relevant as it will affect the Public Official's statement most if answered affirmatively or negatively.

+1 A.
Regards,

kinjiGC · Answer

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?

A. Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes ->  looks good , candidate of variance test to be sure.

Evaluate argument, lets take a variance test.

Lets say A) yes
Then the conclusion breaks. The conclusion is "this is extremely unlikely".
Lets say A) No.
Then the conclusion Stays.

So this is the correct answer.

B. What proportion of people who live near high-voltage power lines believe that those lines may cause health problems ->  it is not about people belief. 
C. Whether high-voltage power lines are routed near residential dwellings in urban areas ->  We are talking about areas in general.  
D. What specific diseases or conditions are suspected by some researchers to result from exposure to magnetic fields from high-voltage power lines ->  Specific disease is out of scope of the argument 
E. What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines ->  Average strength of magnetic field in the home is used for comparison, It is not required to know what is the actual value of the magnetic field. The argument deals with whether the average strength is bad enough to cause any issue.

Abhishek009 · Answer

1. Magnetic fields from high-voltage power lines can cause health problems to people living near it.

2.  Beyond a distance of few feet , the strength of the magnetic fields is  less than the average strength of magnetic fields in homes living away  from those lines.

Which of the following would it be most useful to establish in order to evaluate the public health official's argument?

A. Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes

The 2nd sentence clearly mentions effects of power lines located away from residential homes - This can be a possible answer.

B. What  proportion  of people who live near high-voltage power lines believe that those lines may cause health problems

We have no data to comment on Proportion - Incorrect.

C. Whether high-voltage power lines are routed near residential dwellings in urban areas

The statement provided explicitly claims that " Magnetic fields from high-voltage power lines can cause health problems to people living near it. " so it is not desirable to place power lines near residential dwellings in urban areas.

The Official mentions that establishing power lines - Incorrect.

D.  What specific diseases or conditions  are suspected by some researchers to result from exposure to magnetic fields from high-voltage power lines

No information provided for specific diseases/conditions - Incorrect

E.  What is the average strength of magnetic fields in workplaces   that are not located near high-voltage power lines

Average strength of magnetic fields in workplaces can't be predicted , because we don't have such data. - Incorrect.

Hince , IMHO - A

Dutta · Answer

Guys
The same question I got in actual GMAT in 2015 March.
also I have seen Prep Qn(s) are quite in tune to actual GMAT Qns.

FYI only thanks.

arvind910619 · Answer

Imo A
The argument tells us that fear of developing disease by living near high voltage lines is not correct as they are exposed to much less strength of magnetic field the people living is areas far off from such lines are exposed to .
So if we whether those people who live far off can develop disease because of magnetic field then we can determine whether people living near such high voltage lines are prone to diseases.

zvazviri · Answer

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?

A. Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes.  The premise is that the strength of magnetic field of high voltage power lines < the strength of magnetic field in homes not located close to power lines. If the magnetic field in homes is still harmful, magnetic field of high voltage might still be harmful. However, if the magnetic fields in those homes do not cause health problems, then the high voltage power lines won't cause health issues since the magnetic field is even weaker

B. What proportion of people who live near high-voltage power lines believe that those lines may cause health problems  What people believe is irrelevant; the magnetic field may not be harmful even when people believe it is

C. Whether high-voltage power lines are routed near residential dwellings in urban areas  The argument can still hold even when high-voltage power lines are routed near dwellings

D. What specific diseases or conditions are suspected by some researchers to result from exposure to magnetic fields from high-voltage power lines   Type of disease is irrelevant. We want to know whether high voltage power lines affect health. What diseases they do it doesn't matter

E. What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines  Workplaces? Argument is about homes. Out of scope

priya sri · Answer

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?

A. Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes 
B. What proportion of people who live near high-voltage power lines believe that those lines may cause health problems 
C. Whether high-voltage power lines are routed near residential dwellings in urban areas 
D. What specific diseases or conditions are suspected by some researchers to result from exposure to magnetic fields from high-voltage power lines
E. What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines

Here conclusion is-- 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. 
 Prethinking- 
I have to evaluate the argument.
Check for options,,,if negated its going to disturb the conclusion.

Option A-Whether magnetic fields in homes that are  not  located near high-voltage power lines can cause health problems for the residents of those homes .

iF YES--then argument can sustain
If No-it disturbs statement that---magnetic field can cause health issues to the people.

B-proportion-out of scope
C-lines in urban area or rural area.......concerned about effect of magnetic lines that can cause health issues. Criteria is health issue here
D-criteria of health issues,,,not cardiac disease or thyroid issue 
E-What is the average strength of magnetic fields in workplaces that are not located near high-voltage power lines

knowing average strength has nothing to do here. Knowing whether manetic field causes issue to public health or not--is the main concern

Try again and again till you succeed. Never compromise,..
priya

DavidTutorexamPAL · Answer

hey Rebekah , to answer your question in this thread - https://gmatclub.com/forum/public-healt ... s#p2159688 We are asked to substantiate not the public health officials argument, but rather the opposite - the argument that this is extremely unlikely. The claim that this is unlikely rests on the assumption that the magnetic fields in people's homes not near lines are not dangerous. A) gives us data on whether this is true. Is this clearer now?

hero_with_1000_faces · Answer

Hello  GMATNinja  sir,  VeritasKarishma

I have one doubt, in the premise it is given that the magnetic field strength is  less than  the average strength of Homes.
Thus as the strength is already weaker than Homes, does it makes sense to consider whether magnetic field at home can cause health problems for the residents or not.

Thanks

100mitra · Answer

Reasoning What additional evidence would most help determine:  
Whether magnetic fields from high-voltage power lines cause health problems for people who live near the lines?

The public health official argues that 
 Premise:  Power lines’ magnetic fields probably do not cause health problems beyond a few feet from the lines, 
because those magnetic fields are weaker than magnetic fields usually are in homes far from such lines.

Assumption:  
1. Magnetic fields in homes far from the lines do not cause health problems 
2. People who live near the lines do not spend much time within a few feet of them. 
Therefore, look for an answer option that indicates 
whether one or both of these assumptions is correct.

A  Correct.  This information would straightforwardly indicate 
whether the first assumption discussed above is true!

B People’s beliefs about 
whether the power lines cause health problems may be ill-founded and mistaken; 
they are not relevant to 
whether magnetic fields can cause health problems  - Wrong

C This would indicate 
whether many people live near the power lines, but not 
whether those who live near the lines suffer health problems as a result  - Wrong

D Without further information 
(whether the incidence of such diseases or conditions is greater among people who live especially near higher-voltage power lines), 
knowing which specific health problems the researchers think 
the lines cause would suffice to evaluate the public health official’s argument  - Wrong

E The argument concerns magnetic fields in homes, 
not magnetic fields in workplaces; 
but knowing how strong the magnetic fields are even in homes 
would not suffice to 
know whether such magnetic fields cause health problems or not  - Wrong

krndatta · Answer

KarishmaB  
Ma'am, 
Can you please explain option A once with the variance test and its subsequent impact on the conclusion.

KarishmaB · Answer

I only know the variance test in Stats, not in CR so I am not sure about what you are talking but I am guessing you mean the Yes/No test.

- Magnetic fields from power lines can cause health problems to people living close by.
- Far away homes have stronger magnetic fields (caused by something else at home) than the strength of magnetic field close to power lines.

Conclusion: It is unlikely that magnetic fields from power lines cause health problems to people living close by.

(A) Whether magnetic fields in homes that are not located near high-voltage power lines can cause health problems for the residents of those homes

Yes - Magnetic fields at home far from power lines can cause health problems. People in far away homes are already exposed to stronger magnetic fields but are ok. Then power line fields which are weaker than these magnetic fields are not likely to cause harm.

No - Magnetic fields at home are harmless. Then, whether they are strong or weak is irrelevant. They could be very very strong but they will still be harmless. Then how can we compare the strengths of the two types of fields and say that since power lines fields are weaker than magnetic fields at home, we don't need to worry? The weak power line fields, even though weaker than home magnetic fields, could be causing damage to people's health. We cannot give a clean chit to the power line fields by saying that they are weaker than magnetic fields already present at home. Then the reasoning of the argument doesn't work.

Hence, in the two cases, the conclusion is affected differently.

egmat · Answer

The official says: Power line magnetic fields (beyond a few feet) are  weaker  than average home magnetic fields →  therefore  power lines are unlikely to cause health problems.

The Hidden Assumption:
 This reasoning only works  if  the magnetic field level in average homes is   safe  . The official is using home field strength as a "safe benchmark."

Variance Test on Option A:
"Whether magnetic fields in homes NOT near power lines can cause health problems"

Scenario 1: YES  (home fields CAN cause health problems)
- If home-level magnetic fields are dangerous...
- And power line fields (at distance) are similar in strength...
- Then power line fields could  also be dangerous! 
- Result: Conclusion is  WEAKENED

Scenario 2: NO  (home fields CANNOT cause health problems)
- If home-level magnetic fields are safe...
- And power line fields are even weaker than home fields...
- Then power line fields are likely  safe too 
- Result: Conclusion is  STRENGTHENED

Since answering YES weakens the conclusion and NO strengthens it, Option A directly evaluates the argument.

Key Takeaway:
In Evaluate questions, the correct answer must have different impacts on the conclusion depending on whether you answer YES or NO. Option A passes this test perfectly!

Public health official: Some researchers suspect that magnetic fields

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Public health official: Some researchers suspect that magnetic fields

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