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# Riders who wear bicycle helmets can greatly reduce the risk of

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GMAT 1: 660 Q48 V33
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Riders who wear bicycle helmets can greatly reduce the risk of  [#permalink]

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24 Aug 2015, 11:58
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Difficulty:

25% (medium)

Question Stats:

69% (01:15) correct 31% (01:23) wrong based on 269 sessions

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Riders who wear bicycle helmets can greatly reduce the risk of significant injury. Therefore, doctors working in an emergency room can expect that out of cyclists admitted to hospitals those wearing bicycle helmets will have injuries that are less severe than those not wearing a helmet.

Which of the following is necessary to evaluate the argument?

A) The probability that those cyclists admitted to an emergency room have suffered similar accidents in the past
B) The durability of bicycle helmets over the course of many years
C) The number of riders wearing bicycle helmets compared to the number not wearing helmets
D) Whether the bicycling activities of cyclists using a helmet differs from the activities of those not wearing a helmet
E) The number of medical staff who are in the emergency room when an injured cyclist arrives

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Re: Riders who wear bicycle helmets can greatly reduce the risk of  [#permalink]

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24 Aug 2015, 13:13
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Harley1980 wrote:
Riders who wear bicycle helmets can greatly reduce the risk of significant injury. Therefore, doctors working in an emergency room can expect that out of cyclists admitted to hospitals those wearing bicycle helmets will have injuries that are less severe than those not wearing a helmet.

Which of the following is necessary to evaluate the argument?

A) The probability that those cyclists admitted to an emergency room have suffered similar accidents in the past
B) The durability of bicycle helmets over the course of many years
C) The number of riders wearing bicycle helmets compared to the number not wearing helmets
D) Whether the bicycling activities of cyclists using a helmet differs from the activities of those not wearing a helmet
E) The number of medical staff who are in the emergency room when an injured cyclist arrives

Dear Harley1980,
I'm happy to respond. This question was written by my friend Chris Lele at Magoosh.

The prompt makes a distinction between bicyclist with vs. without helmets, concluding that the latter will have more severe head injuries. Certainly if all bicyclists do approximately the same things, then all things being equal, having a helmet would prevent more serious injuries. The trouble is: it's not tenable to assume that all bicyclists do more or less the same things. What if the true daredevils, doing crazy dangerous moves, all wear helmets, and the bicyclists who don't wear helmets are only doing the very safest things, on flat paved surfaces with no traffic nearby? It would be conceivable that, despite helmets the daredevils would get more serious head injuries than do the folks without helmets doing super-safe things.

That is a weakener. Sometimes the point "necessary to evaluate" follows the logic of a strengthener or a weakener.

Here, let's look at the answer choices.
(A) The probability that those cyclists admitted to an emergency room have suffered similar accidents in the past
Getting a head injury before might lead to a more serious injury this time. But this does not allow us to draw any distinction between bicyclists with vs. without helmets.

(B) The durability of bicycle helmets over the course of many years
This would be more relevant if we were comparing bicyclists with old helmets vs. with new helmets. We don't know anything about the ages of the helmets for those using helmets. This doesn't tell us anything about folks with vs. without helmets.

(C) The number of riders wearing bicycle helmets compared to the number not wearing helmets
Interesting, but the prompt is not numerical. It says "more serious head injuries" --- this may imply an average or may be about, say, the top 10% worst head injuries. In neither case would absolute numbers matter, whether one group was larger or smaller than the other group in terms of sheer numbers. This is irrelevant.

(D) Whether the bicycling activities of cyclists using a helmet differs from the activities of those not wearing a helmet
This is connected to the weakener we were exploring above. If all high-risk daredevils are helmet wearers, and all non-helmet wearers are doing super-safe risk-free things, then that might undercut the argument, as we saw above. This is promising as an answer.

(E) The number of medical staff who are in the emergency room when an injured cyclist arrives
Again, does not allow us to make a distinction between bicyclists with vs. without helmets.

Does this make sense?
Mike
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Mike McGarry
Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)

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Riders who wear bicycle helmets can greatly reduce the risk of  [#permalink]

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02 Jun 2018, 01:00

Official Explanation Magoosh:

If a person is wearing a bicycle helmet, then, all things being equal, that’s person injury would be less severe than had they not been wearing a helmet. The thing is we can’t assume all things are equal between one who wears a helmet and one who does not wear a helmet.

Therefore, to properly evaluate the argument, we have to be able to show that those wearing helmets were engaging in similar activities as those not wearing helmets. For instance, if those who wore helmets tended to go down steep trails at high speeds and those who did not wear helmets rode around the neighborhood, the argument is not valid. This leads us to (D).

(A) does not talk about the severity of accidents. We want to know if there is a fundamental difference in the severity of accidents between the helmet clad and the non-helmet clad.

(B) superficially seems as though it would work. We don’t know if those admitted to the emergency room are wearing old helmets. If so, then it would be important to know (B), since helmets that were old and no longer offered protection would compromise the argument.

(C) is wrong because the conclusion is not concerned with the number of injuries. Rather, it's concerned with the severity of injuries and so this answer choice is out of scope.

(E) does not relate to the issue: are the two groups—the helmet wearing and the non-helmet wearing—equivalent?

FAQ: Is this a strengthening/weakening question? How do we approach questions like this?

A: This kind of question: "which would be most useful to evaluate the argument?" involves understanding the assumptions for the argument. The correct answer choice will tell us whether a key assumption for the argument is true or not. Basically, the question is asking us what information we need to know in order to decide whether the conclusion of the argument is valid.

For this question, the argument is that bicycle helmets reduce injury, therefore cyclists who were wear helmets will have less severe injuries.

One assumption of this argument is that cyclists with helmet do not engage in more risky/dangerous behavior. So, to evaluate the argument we would need to know answer choice (D) "whether the bicycling activities of cyclists using a helmet differs from the activities of those not wearing a helmet."

FAQ: Why is choice B wrong?

A: The problem with (B) is that we aren't given any information regarding the age of the helmets in question. Maybe all these helmets are new -- we just don't know. So (B) doesn't help us as much as (D).
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Riders who wear bicycle helmets can greatly reduce the risk of &nbs [#permalink] 02 Jun 2018, 01:00
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