Researchers recently discovered an unusually high concentration of har

Question

Researchers recently discovered an unusually high concentration of harmful metals in the water supply of Dunbarton county. They further found that, with a costly new water filter system installed in their homes, residents were able to filter out almost all of the harmful metals in the water supply. For this reason, all the residents of Dunbarton county should have the filter system installed in their homes, regardless of expense.

If true, which of the following would most weaken the above conclusion?

A. Researchers could not discover how the harmful metals were entering the water supply.

B. The increased levels of harmful metals were insufficient to result in significant health effects.

C. The researchers failed to investigate the possibility of harmful microorganisms and other contamination in the county's water supply.

D. The researchers found that people who tried to purify their water by boiling it were just as likely to ingest increased levels of harmful metals as people who drank straight from the tap.

E. Researchers found that, over time, the levels of harmful metals in the water supply did not vary significantly and remained consistently high.

mrinal0308 · Answer

Ans : B 
Because if there are no significant health hazards happening due to intake of this water, there is no necessity of installing the expensive equipment to filter water at home. Hence the argument is weakened.

chesstitans · Answer

"For this reason" indicates that there is only one main premise.
There are 2 or 3 patterns in option choices.

Ratnaa19 · Answer

Can you explain why C is not the correct choice ..
I was stuck between b and c

lybeaver · Answer

Well, I put B in the contender, but then I rejected B because of the word "significant health effects", the increased levels of harmful metals were insufficent to result in significant health effects, but it actually can result in unsignificant health effects or health effects in general, therefore, the residents should have the filter system installed in their homes. Then this choice should strengthen the plan

Please correct my reasoning above. Thanks!

Please correct my reasoning above. Thanks!

XyLan · Answer

lybeaver , It's  good  to be watchful!
However, Let's  Deep-dive !
  Conclusion:  
 New WaterFlterSystem filters almost all ---------> All the residents SHOULD have the WaterFlterSystem installed in their homes,  regardless  of expense.

Pre-Think:  
 Assumption: The increased levels of harmful metals are harmful ENOUGH to cause adverse effects on health.

B.  The increased levels of harmful metals were insufficient to result in significant health effects.
 If the increased levels of harmful metals were  INSUFFICIENT  to result in  significant  health effects, then WHY should the residents  NEED  to install it.
  - That too, at whatever expense.

To answer your query:  
  Notice the passage states that the increased levels are  INSUFFICIENT  to result in  significant  health effects.
Implying,  - it actually CAN result in insignificant health effects or health effects in general. , is an  inference  mistake of the answer choice.
 Did OptionB states that the increased levels of harmful metals were  sufficient  ENOUGH to affect in  health effects  OR  health effects in general ?  NO.  
 Look at this way:  
If one does NOT study diligently and work hard --------> One would fail.
 Does it imply? 
if one DOES study diligently and work hard --------> One will DEFINITELY pass.
  NO . It's  NOT   necessarily  conclusive.   There might be  other factors  such as test-taking ability, test-surroundings, mindset, mental condition, etc.     
You did an error of  mistaken-negation  of a conditional statement.
  If X ------> Y    -----   does NOT imply   ----->       If NOT X ------> NOT Y    
Moreover, 
  Something CAN  does NOT  necessarily  mean it ACTUALLY does, unless backed by the   coherent   answer choice.   - Capacity vs Certainty

Even if increased levels CAN result in  in significant health effects, the effects are STILL insignificant.   -  Unlikely  to cause adverse health hazard/issue.

TakeAway:   
You lose this Q not because you did not know how a weakener works ( Infact, I believe you  very well  do! ) , but because you did an  inference mistake  from a  right-answer choice.  - An  unintended  yet,  costly  mistake in GMAT.
 Always   ASPIRE  to find 4  incorrect  answer choices.

lybeaver · Answer

Xylan : Thanks so much! Your explanation is an eye opener!

m1033512 · Answer

IMO B

Conclusion : residents should install filters due to increased metals .

If the increased metals have no negative health impact , then why we should filter them .

We do not need filter at all.

So B is correct answer .

Posted from my mobile device

mokiburnsred · Answer

I was down to B and E and chose E in the end. Could someone please tell me why E was eliminated?

VirFortis · Answer

What is the source of this question?

There is no mention of the information - that the level of contamination has increased. It just says that high level of contamination is found.

So, option B suggesting the "increased" contamination seems out of context while option C which states that the other contamination can also be part of the water seems like something to weaken the conclusion but again it doesn't talk about the fact if the filter can help with those.

So, the argument of installing the filter based on the fact that almost all harmful contamination is removed by it is shaky at its core.

Posted from my mobile device

VirFortis · Answer

Sorry, but I am not able yo find - "increased level" - causing harm statement in the passage. Rather it says - High level contamination - > causes harm - > filter helps - > install filter. So we should attack premise - filter helps.

What am I doing wrong here?

Please guide me.

Posted from my mobile device

VerbalBot · Answer

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Researchers recently discovered an unusually high concentration of har

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