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Statistics published by the US Department of Transportation [#permalink]
05 Apr 2004, 19:15

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Difficulty:

(N/A)

Question Stats:

100% (01:59) correct
0% (00:00) wrong based on 2 sessions

Statistics published by the US Department of Transportation show that nearly 80 percent 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 percent of all traffic accidents resulting in fatalities
B) Eigthy percent of all persons arrested for driving at a speed over the posted speed limit are intoxicated
C) Fifty percent 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) Ninety percent of all driving time is registered within a 25-miles radius of the driver's home and at speeds less than 50 miles per hour

E) Ninety percent of all driving time is registered within a 25-miles radius of the driver's home and at speeds less than 50 miles per hour

If most fatalities occur within 25 miles of the driver's home and at speeds less than 50 miles per hour, and if 90% of driving time is spent within 25 miles of the driver's home and at speeds less than 50 miles per hour, then the driver is not safer. Even though he/she may drive on highways that are outside the 25 mile radius and with speeds higher than 50 miles per hour, 90% of his/her driving would still occur near his/her home.

I thought of different explanation because the argument clearly says "if you drive in the area which is more than 25 miles away and above 50 mph"

The argument is kind of stupid because to go 25 miles away first you have to travel the first 25 miles. Even if you travel the first 25 miles under 50 MPH you are at a risk because the stats say that. So you are never safe. Since the argument is not sound we can just strengthen the stats and let it fall by itself. I believe E strengthens the statistics provided, basically making the author refute his/her claim.

E shows that the US Department of Transportation's data is biased towards traffic fatalities that occur at speeds of under 50 miles per hour and within 25 miles of home.
Let's take a number example. Total population under study is 10000.

Say you have 9000 who drive at a speed under 50 miles per hour and who live within 25 miles of home. --> Category 1

Then 1000 people under study do not fall under this category because they either drive faster than 50miles/hr or they live beyond 25 miles of home. --> Category 2

The above 2 categories are consistent with E which claims that 90% of all driving time is registered within a 25-miles radius of the driver's home and at speeds less than 50 miles per hour

If we say that there are 100 accidents and 80% of those accidents come from category 1, as the argument claims, then 80/9000 = .88% likelihood of having an accident.
Remainder 20%, 20 persons, will represent a likelihood of accident of: 20/1000 = 2% for category 2. Thus, does the conclusion that 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 (category 2) stand? The proof that there are more data "logged" under category 1, as E says, will clearly weaken the above conclusion