Statistics published by the U.S. Department of Transportation show tha

Question

Statistics published by the U.S. Department of Transportation show that nearly 80% of all traffic fatalities occur at speeds of under 50 miles per hour and within 25 miles of home. Therefore, you are safer in a car if you are driving at a speed over 50 miles per hour and not within a 25-mile radius of your home.

Which of the following, if true, most weakens the conclusion of the argument above?

(A) Teenage drivers are involved in 75% of all traffic accidents resulting in fatalities.

(B) 80% of all persons arrested for driving at a speed over the posted speed limit are intoxicated.

(C) 50% of the nation’s annual traffic fatalities occur on six weekends that are considered high-risk weekends because they contain holidays.

(D) The Department of Transportation statistics were based on police reports compiled by the 50 states.

(E) 90% of all driving time is registered within a 25-mile radius of the driver’s home and at speeds less than 50 miles per hour.

Source:  Master GMAT

nayanparikh · Answer

Let's breakdown the argument. 
Premise: It says most of accident occurs within 25 miles from home and drive speed is below 50 miles per hour. 
Conclusion: If you cross 25 miles from home and are above 50 miles you will be safer.
Assumption: Within the 25 miles drive from home the driver never exceeds 50 miles per hour.
Now form the options we need to pick such argument which make the conclusion invalid or breaks it.

(A) Teenage drivers are involved in 75% of all traffic accidents resulting in fatalities.
 Ans: Not worried about the demographic of the drivers involved in the accident. 
(B) 80% of all persons arrested for driving at a speed over the posted speed limit are intoxicated.
 Ans: Out of Scope 
(C) 50% of the nation’s annual traffic fatalities occur on six weekends that are considered high-risk weekends because they contain holidays.
 Ans: No reason has been given for the accident to occur, it might be traffic, it might be bumpy roads, poor lighting etc. 
(D) The Department of Transportation statistics were based on police reports compiled by the 50 states.
 Ans: Out of Scope 
(E) 90% of all driving time is registered within a 25-mile radius of the driver’s home and at speeds less than 50 miles per hour.
 Ans: Yes if this taken as true this will break the conclusion or will make it invalid

Thanks.
With Regards,
-Nayan Parikh
 +1 for kudos

kumarparitosh123 · Answer

A tough one. I initially chose A but after seeing the description of nayan Parekh, I understood where I was wrong.

Nice explanation Nayan.
+1

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avinashvpec · Answer

Nayan, I didn't get the reasoning for E, Option E sounds very close to the assumption that you have mentioned. Although I agree with the assumption you have mentioned but I am not able to link it to "how E weakens the argument". Can you please explain more w.r.t to the mentioned assumption.

Regards
Avinash

Sajal089 · Answer

i still don't get it. 
can someone please justify option E.

Sajjad1994 · Answer

Official Explanation

The reasoning in the argument is representative of the fallacy of false cause. Common sense tells you that you are not necessarily safer driving at higher speeds. Moreover, the distance you are from your home does not necessarily make you more or less safe. And it will not do to engage in wild speculation, e.g., people suddenly become more attentive at speeds over 45 miles per hour. The exam is just not that subtle. Rather we should look for a fairly obvious alternative explanation, and we find it in  (E).

The real reason there are fewer fatalities at speeds over 50 miles per hour and at a distance greater than 25 miles from home is that less driving time is logged under such conditions. Most driving originates at home and proceeds at speeds set for residential areas.

(A), (B), and (C)  all seem to make plausible statements, but they are irrelevant to the claim made in the stem paragraph. It is difficult to see how they could either weaken or strengthen the argument.

(D)  has the merit of addressing the statistics used to support the argument, but without further information  (D)  does not weaken the argument—it merely makes an observation. To be sure, if we knew that states were notoriously bad at gathering statistics,  (D)  could weaken the argument. But that requires speculation, and we always prefer an obvious answer such as  (E).

The correct answer is (E).

Statistics published by the U.S. Department of Transportation show tha

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Statistics published by the U.S. Department of Transportation show tha

Prep Toolkit

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