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# A recent report determined that although only three percent

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A recent report determined that although only three percent [#permalink]

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01 Jul 2003, 07:02
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A recent report determined that although only three percent of drivers on Maryland highways equipped their vehicles with radar detectors, thirty-three percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not.

The conclusion drawn above depends on which of the following assumptions?

(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
[Reveal] Spoiler: OA
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Re: A recent report determined .. [#permalink]

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14 Aug 2010, 12:55
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Hey All,

I can explain that difference! Let's take this from the top.

A recent report determined that although only three percent of drivers on Maryland highways equipped their vehicles with radar detectors, thirty-three percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not.

Conclusion: Driver with radar exceed the speed limit more than those with no radar.
Premise: 3% of drivers have radar. 33% of ticketed vehicles have them.
Assumption: Something else about the radar doesn't make you more likely to get ticketed. Speed = tickets.

The conclusion drawn above depends on which of the following assumptions?
(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
PROBLEM: This is the opposite of what we want. The people with radar are clearly getting tickets MORE often than those who do not.

(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
ANSWER: This is dangerous, because most people ASSUME this already (if you get tickets more, it's because you're speeding more). But remember this is the GMAT, we cannot assume this. We can't jump from "more tickets" to "more speeding", as much as our logic nodes may want it.

(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
PROBLEM: We don't need to assume this to make our conclusion. Try negating it, and seeing if that destroys the conclusion (this is a way to test correct assumptions). "The number of vehicles that were ticketed for exceeding the speed limit was NOT greater than the number of vehicles that were equipped with radar detectors." So what? It could still be true that people with radar are speeding more.

(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.
PROBLEM: Even if this might work, it's the OPPOSITE of what we'd want. We'd want to assume that these people were only ticketed ONCE, because if the same person was ticketed multiple times, he might only be one person, in which case the conclusion doesn't work. But the negation of this is: "Many of the vehicles that were ticketed for exceeding the speed limit were NOT ticketed more than once in the time period covered by the report." That HELPS the argument, see? Now we can possibly infer that there are MORE PEOPLE with radar speeding, because there are no duplicates.

(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
PROBLEM: Who cares about stuff outside of Maryland?

Hope that helps!

-t
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02 Jul 2003, 00:20
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Only a tiny fraction of people have the radar detectors. However, one-third of tickets go to people with radar detectors.

Radar detectors are associated with increased incidence of tickets.

But how do we know that those getting caught are speeding regularly?

You don't, unless you assume it (B).

Very tricky because of all the verbiage.
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24 Nov 2010, 20:54
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goalsnr wrote:
A recent report determined that although only three percent of drivers on Maryland highways equipped their vehicles with radar detectors, thirty-three percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not.
The conclusion drawn above depends on which of the following assumptions?
(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.

Let's look at the question stem first. We need to find an assumption. An assumption is a missing necessary premise. Something that will not only strengthen the conclusion but also be essential to the argument.
An assumption is a statement that needs to be added to the premises for the conclusion to be true.

Premises:

Conclusion: Drivers with radar detectors are more likely to exceed the speed limit regularly than other drivers.

There must be a disconnect between the premises and conclusion since there is an assumption. Look carefully. Premises give a connection between radar detectors and vehicles that get speeding tickets. While conclusion concludes a relation between radar detectors and vehicles that exceed speed limit. The assumption must then give a connection between vehicles that get speeding tickets and vehicles that exceed speed limit.
Option (B) gives us that relation.

Lets add it to premises and see if the conclusion makes more sense now:

-Drivers who get speeding tickets are more likely to exceed the speed limit regularly than others. (links speeding tickets to exceed speed limit)

Conclusion: Drivers with radar detectors are more likely to exceed the speed limit regularly than other drivers. (links radar detectors to exceed speed limit) Perfect!

Option (C) only tells us that people without radar detectors were also ticketed. It doesn't strengthen our conclusion at all.
Option (D) tells us that many vehicles were ticketed multiple times. It doesn't say that these vehicles had radar and had been over speeding regularly. Hence option (D) isn't the missing premise either.
You can also apply the Assumption Negation Technique here. If you negate (B) conclusion cannot be drawn.
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15 Mar 2005, 00:44
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3% of drivers on maryland highways equip their vehicles with radar detectors
31% of all vehicles ticketed for exceeding the speed limit were equip with them
Drivers who equip their vehicles with radar detectors are more likely to exceed speed lmiit regularly than driver who do not <-- conclusion

(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
- does not hold up the conclusion

(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
This one holds up the conclusion. We're told a large percentage of vehicles with radar detectors were ticketed for speeding. Then (B) says those who are ticketed are likely to exceed the speed limit regularly. So the conclusion that vehicles with radar detectors exceed the speed limit regularly is true.

(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
- not important.

(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.
- does not help the conclusion

(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
- out of scope
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Re: A recent report determined .. [#permalink]

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07 Aug 2011, 17:36
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Guys, classic scope shift as indicated by mismatch of subject in the main assertion and the assumption choices – driver vs vehicle! The element that needs to be connected for the argument to work is the subject ‘driver’. In choice D the subject morphs into something slightly different, which seem consistent, or even inferable from the argument. Hence B.

Another form of common scope shift is when the author uses a word or concept in two different ways where the intent is to blur the main topic - equivocation. For example, ‘airplanes seats have been designed for safety’ is different from saying ‘airplanes seats are safe’.

Another common shift arises in the main conclusion itself when we find something else comes out of nowhere, in which case the job is to connect that ‘something else’ in the conclusion with something in the premise in order to make the argument work. Hence we make it focal point of assumption hunt.
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Re: Highway drivers problem cant understand explain [#permalink]

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24 Apr 2013, 16:03
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FACT 1:
A recent report determined that although only 3 percent of drivers on Maryland highways equipped their vehicles
FACT 2:
33 percent of all vehicles ticketed for exceeding the speed limit were equipped with them.
CONCLUSION:
Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly
than are drivers who do not.

The conclusion drawn above depends on which of the following assumptions?

Even though a few vehicles have radars, 33% of the ticketed had it. The conclusion, as often happens in the GMAT when we have numerical data, assumes the validity of the data itself: uniformity, no distortions, ...
So before reading the answers we have to keep this in mind: the data must be "true", must represent the reality.
Movin on to the answers, we now can see why B is correct.

(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly
than are drivers who are not ticketed.

With B we know that the data does represent the reality, and the conclusion is not based on few cases. If you want with assumption cases you can negate the option and see if the argument holds.
If you do so you obtain "Drivers who ... are less likely to"; here it's easier to see that the conclusion (without B) is based on unreliable data.

Hope this helps, let me know
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Re: A recent report determined that although only three percent [#permalink]

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07 Aug 2013, 15:48
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We'll attack this question with some framework + prethinking.

Framework: Expectation vs Actuality
Pre-thinking: Link the two relevant topics

This question starts off with the expectation vs actuality framework
Expectation: 3% (low percentage) with radar detectors ->might expect 3% of ticketed cars to have radar detectors
Actuality: 3% (low percentage) with radar detectors -> actually 33% of ticketed cars have radar detectors

Conclusion: Those using radar detectors are MORE likely to exceed speed limit REGULARLY.

Keep in mind that the word "regularly" adds a dimension of "degree" into the conclusion. It's not a simple relationship between "detector = speed more", but rather "detector = consistently speed more"

So our pre-thinking should be to find an answer choice that connects those two topics:
1) something to do with "detector"
2) something to do with "consistently speeding more" -- keyword 'consistently' is important

(B) [Drivers who are ticketed for exceeding the speed limit ] are [ more likely to exceed the speed limit regularly]
than are drivers who are not ticketed.

So does (B) talk about the detector? Not directly BUT it does so indirectly.
[Drivers who are ticketed for exceeding the speed limit ]
We already established before that a good percentage of those who are ticketed (33%) are those WITH detectors. Thus (B) is already referencing this segment of the population. Then the second half says this group (those with detectors) are more likely to exceed the speed limit REGULARLY -- fully captures the conclusion we had. In fact, it almost sounds like a repeat of the conclusion -- but it does so by substituting that first part ("detectors") with something slightly different.

(A) [ Drivers who equip their vehicles with radar detectors ] are [less likely to be ticketed for exceeding the speed
limit ]
than are drivers who do not.

1) "detector" -- YES
2) "consistently speeding more" -- NO, goes in opposite direction and says LESS likely.

(C) [ The number of vehicles that were ticketed for exceeding the speed limit ] was greater than the number of
vehicles that were equipped with radar detectors.
1) "detector" -- no, this is talking about the # of vehicles...not the population of those that speeded. Notice the other answer choices reference "drivers" -- not "the number of vehicles"
2) "consistently speeding more" -- no

(D) [ Many of the vehicles that were ticketed for exceeding the speed limit ] were ticketed more than once in the
time period covered by the report.
1) "detector" -- no, this is talking about some detail about a portion of the vehicles -- we only care about the drivers that used the "detector" -- not the details about some irrelevant segment
2) "consistently speeding more" -- no

(E) [ Drivers on Maryland highways ] exceeded the speed limit more often than did drivers on other state
highways not covered in the report.

1) "detector"-- no, talks about drivers in Maryland as a whole. The conclusion only cares about drivers who used the detector, not the whole group.
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01 Sep 2004, 07:10
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saurya_s wrote:
171. A recent report determined that although only three percent of drivers on Maryland highways equipped their vehicles with radar detectors, thirty-three percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not. The conclusion drawn above depends on which of the following assumptions?
(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.

B must be the answer. The argument cites high incidence of radar-equipped cars BEING TICKETED but derives a conclusion about how often these cars EXCEEDED THE SPEED LIMIT. Clearly, in the author's opinion those drivers who are often ticketed often exceed the speed limit. Thus, B is the missing link
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01 Sep 2004, 09:28
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I think the answer is D.

Assuming there are 1000 drivers on Maryland highways. 3% or 30 cars are equipped with radar detectors.

Let's say 200 cars were ticketed for speeding. 33% or 66 cars were equipped with radar detectors. this means that some cars were ticketed more than once, else one can't have 66 cars with radar detectors with originally 30 cars equipped with radar detectors.

D states this assumption.
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Re: A recent report determined .. [#permalink]

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23 Sep 2010, 11:08
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Did my best, but please don't PM me anymore, as I'm taking a break from the forums.

-t
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Re: A recent report determined that although only 3 percent of [#permalink]

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18 Feb 2013, 10:07
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Expert's post
sagarsingh wrote:
abhichar wrote:
[color=#0000ff]A recent report determined that although only 3 percent of drivers on Maryland highways equipped their vehicles with radar detectors, 33 percent of all vehicles ticketed for exceeding the speed limit were equipped with them.
Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the spped limit regularly than are drivers who do not.

The conclusion drawn above depends on which of the following assumptions:

Everything written above makes sense, I just want to focus on the main takeaway of this question as this issue comes up over and over again in Critical Reasoning. The question sets you up with drivers who get ticketed, and then a conclusion is made for all drivers who exceed the speed limit regularly. The GMAT frequently makes these kinds of leaps in logic, and the answer is always the choice that reconciles the group given in the premise (ticketed for speeding) with the group extrapolated for in the conclusion (regularly exceeds the speed limit).

Once you learn how to spot these questions, either through clear conceptual understanding or myriad similar examples, these are easy breezy questions. And if you can get a few easy questions on the exam, then you have more time for the head scratchers.

Hope this helps!
-Ron
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01 Sep 2004, 11:30
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kedar1972 wrote:
I think the answer is D.

Assuming there are 1000 drivers on Maryland highways. 3% or 30 cars are equipped with radar detectors.

Let's say 200 cars were ticketed for speeding. 33% or 66 cars were equipped with radar detectors. this means that some cars were ticketed more than once, else one can't have 66 cars with radar detectors with originally 30 cars equipped with radar detectors.

D states this assumption.

Be careful when assigning arbitrary numbers to a problem dealing with percentages. If you were to choose 10 tickets assigned, and 1000 drivers, the 'assumption' is not necessary.

The conclusion
Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not

The conclusion is "more likely to speed regularly", this at the least requires some connection between regular speeding at ticket assignment.

B is this assumption.
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A recent report determined that although only three percent [#permalink]

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02 Nov 2009, 06:22
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A recent report determined that although only three percent of drivers on Maryland highways equipped their vehicles with radar detectors, thirty-three percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not.
The conclusion drawn above depends on which of the following assumptions?
(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.

OA is
[Reveal] Spoiler:
B
. What's wrong with
[Reveal] Spoiler:
D
?
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Re: A recent report determined that although only 3 percent of d [#permalink]

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22 Nov 2011, 22:50
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IMO D. Only 3% of vehicles equipped with radar comprise of 33% of the tickets. Inthis case only two assumptions are possible:

1. The total number of tickets were very less and the card with radars were maximum out of them. For example lets say that out of a total of 100 cars, 3 were equipped with radar and all three were ticketed out of say total of 10 cars ticketed.

2. The cars with radar were ticketed multiple times to form a considerable percentage.

Option D satisfies the second option.
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Re: CR Practice ::A recent report determined tha [#permalink]

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14 Mar 2012, 17:44
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It's definitely a tricky one .

The conclusion states that drivers with radar detectors speed more REGULARLY than those who do not carry radar detectors. Notice how I highlighted the word 'regularly.'

The conclusion is based on the fact that 33% of those ticketed carry radar detectors (whereas only 3% of total drivers are ticketed). From this fact alone can we say that radar-detector drivers speed regularly? They obviously sped once - they got a ticket. But there is no way we can say that they speed regularly. So this is an assumption that the argument rests on, the assumption addressed in (B):

(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.

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Highway drivers problem cant understand explain [#permalink]

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24 Apr 2013, 15:42
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A recent report determined that although only 3 percent of drivers on Maryland highways equipped their vehicles
with radar detectors, 33 percent of all vehicles ticketed for exceeding the speed limit were equipped with them.
Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly
than are drivers who do not.

The conclusion drawn above depends on which of the following assumptions?

(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed
limit than are drivers who do not.
(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly
than are drivers who are not ticketed.
(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of
vehicles that were equipped with radar detectors.
(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the
time period covered by the report.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state
highways not covered in the report.

Last edited by Zarrolou on 24 Apr 2013, 16:04, edited 1 time in total.
Edited the question
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Re: Highway drivers problem cant understand explain [#permalink]

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24 Apr 2013, 18:27
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Consider, There are 1000 drivers on Maryland highways.
3% i.e. 30 vehicles doesn't have radar detectors with them... (from data in CR)... (I)

Consider, 60 vehicles are ticketed for exceeding the speed limit
33% i.e. 20 vehicles didn't have the radar detectors.. (from data in CR)... (II)

From I & III,
20 vehicles with no radar detectors were out of 30 vehicles. Now consider, If 120 vehicles were ticketed, there would around 40 vehicles with no radar detectors.
Data seems to be inconsistent.

If (I) and (II) both are correct, we could say that overall vehicles are ticketed multiple times. So, Option (B) is correct.
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A recent report determined that although only three percent [#permalink]

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20 Jul 2016, 15:03
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Expert's post
ashutoshsh wrote:
ywilfred wrote:
3% of drivers on maryland highways equip their vehicles with radar detectors
31% of all vehicles ticketed for exceeding the speed limit were equip with them
Drivers who equip their vehicles with radar detectors are more likely to exceed speed lmiit regularly than driver who do not <-- conclusion

(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
- does not hold up the conclusion

(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
This one holds up the conclusion. We're told a large percentage of vehicles with radar detectors were ticketed for speeding. Then (B) says those who are ticketed are likely to exceed the speed limit regularly. So the conclusion that vehicles with radar detectors exceed the speed limit regularly is true.

(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
- not important.

(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.
- does not help the conclusion

(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
- out of scope

Hey!
Why is option C not important. I agree, the conclusion says that drivers with radar are more likely to exceed speed limit more regularly than drivers who do not. But this conclusion is based on the evidence that only 3% of drivers have radars and 33%of all vehicles ticketed were equipped with radar. From this evidence, the assumed that no. of vehicles that were ticketed for exceeding the speed limit was greater than the n. of vehicles with radar.

Let us analyze the argument using two intersecting sets:
Vs = ticketed vehicles
Vr = vehicles having radar detectors

Vr = 3%
Vr' = 97%

Vr∩Vs = 33% of Vs
Vr'∩Vs = 67% of Vs

We see that although Vr is very small compared to Vr', Vr∩Vs is much larger compared to Vr'∩Vs. Hence it is concluded that Vr vehicles are more likely to exceed speed limits ( i.e., lie within the intersection of the 2 sets) than Vr' vehicles are.

Now, assumption C: Vs>Vr

Negate this: Vs<Vr, and see if the argument breaks down.

Even if Vs<Vr, the above conclusion may still be valid. It does not matter which set is bigger to arrive at the conclusion. (Try drawing various sizes of Vr and Vs yourself; you would then see the concept more clearly)
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A recent report determined that although only three percent [#permalink]

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01 Sep 2004, 05:33
171. A recent report determined that although only three percent of drivers on Maryland highways equipped their vehicles with radar detectors, thirty-three percent of all vehicles ticketed for exceeding the speed limit were equipped with them. Clearly, drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not. The conclusion drawn above depends on which of the following assumptions?
(A) Drivers who equip their vehicles with radar detectors are less likely to be ticketed for exceeding the speed limit than are drivers who do not.
(B) Drivers who are ticketed for exceeding the speed limit are more likely to exceed the speed limit regularly than are drivers who are not ticketed.
(C) The number of vehicles that were ticketed for exceeding the speed limit was greater than the number of vehicles that were equipped with radar detectors.
(D) Many of the vehicles that were ticketed for exceeding the speed limit were ticketed more than once in the time period covered by the report.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
A recent report determined that although only three percent   [#permalink] 01 Sep 2004, 05:33

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