A recent report determined that although only three percent

[jlucero]

You've got the negating part down, but make sure you understand why that kills the conclusion. Even though people who equip their cars with radar detectors get more tickets, they wouldn't necessarily speed more regularly.

Imagine a scenario where the speed limit is 60. People who have radar detectors drive at 80 half the time and 50 half the time, but they get more tickets than people who don't have radar detectors and drive at 65 all the time.

This is what a world where the assumption (B) is negated.

[rahul_devas]

Let us suppose there are 200 vehicles and 3% of them are equipped with radar detectors i.e 60.

Now let us consider that 100 vehicles have been ticketed in a particular month. Among them 30% have radar detectors i.e
30 vehicles with radar detectors and 70 vehicles without radar detectors.

For the case mentioned above to be true the assumption mentioned as answer is not necessary.


Can somebody clarify?
Thanks
Rahul

[jlucero]

Rahul,

Your scenario doesn't actually address the main conclusion of the argument:

"Drivers who equip their vehicles with radar detectors are more likely to exceed the speed limit regularly than are drivers who do not."

This is what is difficult about this question- people think that regularly speeding and getting tickets are the same thing but they aren't. That's the assumption that the GMAT wants you to ignore and it's exactly what (B) addresses.

[thanghnvn]

I'm confused with this question. Previously, I confused 'regularly' with 'repeatedly'. But now I'm confused with how the conclusion can be true with (b) as assumption.

According to (b), If those 33% fall into 'speed regularly' category then the other 67%, who don't have detectors, would also fall into 'speed regularly' category. Now, how can I conclude that drivers who are equipped with radar detectors (3% vs. 33%) are more likely to 'speed regularly' than other who are not (97% vs. 67%). I mean how can I compare both groups without any solid numbers.

no, no, you're completely ignoring what is most important about that correct answer choice.

the existing problem with the passage is that it conflates "people who are ticketed for speeding" with "people who speed regularly".
since these two things are, in fact, not the same, we need an assumption that the group of people ticketed for speeding actually represents people who speed more often.

--

you would need the same type of assumption if, e.g., the premises of the argument talked about "people convicted of crime X" but the conclusion talked about "people who have committed crime X".

Thank you Ron, your explantion of this question is most eseay to understand. However, I am still confued. I search on the internet to find better explanation but can not find.
Ron, pls, give a similar example and give full explanation of the example. pls write as much as possible. pls understand that what you understand in 5 seconds is what other persons understand in 50 minutes. it is true that gmat CR have some types of logic and understanding these kinds of logic is helpful partcularly.

Thank you Ron.

[jlucero]

Sorry thanghnvn, but you've got a bunch of great explanations here. We know CR is not easy, but you can't ask for a thesis on these problems here. If you have something specific about what's giving you issues here, let us know.

[divineacclivity]

I was not able to get my head around this one atall.
I read it again and again till I understood it. People who were confused like me might benefit from this explanation:

How I perceived it earlier was:
radar detector fitted ones: 3
Total: 100

Ticketed + radar fitted: 3 (say)
Then total ticketed: 10

Conclusion author draws: Clearly, divers with radar fitted vehicles are more likely to exceed speed limit (please note that the conclusion doesn't end at 'speed limit') regularly (the author says such drivers are more likely to exceed speed limit(s) REGULARLY)
That means the author is assuming the ticketed drivers are more likely to exceed speed limits more regularly than those not ticketed.
If you're not able to understand it in one go, please do read over and again and you'd be able to make sense out of it as I did.

For the instructors, I don't have a question here but just wanted to attempt explaining the logic in my own words because it had really been itching the inside of my head. Please feel free to add to it or correct me if I'm wrong. Thanks very much for all your effort in making learning easier for we test-takers (or for us test-takers; I don't know).

[RonPurewal]

This problem rests on one single issue, which is the difference between drivers who speed regularly and drivers who receive speeding tickets.
The point of the problem is for you to recognize that these groups are not the same. (In the U.S., the first group includes just about every single driver on the road, with the exception of some very old people; the second group is much smaller.)

Your numbers don't account for this difference, so they can't adequately explain the problem.

[divineacclivity]

This problem rests on one single issue, which is the difference between drivers who speed regularly and drivers who receive speeding tickets.
The point of the problem is for you to recognize that these groups are not the same. (In the U.S., the first group includes just about every single driver on the road, with the exception of some very old people; the second group is much smaller.)

Your numbers don't account for this difference, so they can't adequately explain the problem.

Sure, Ron. I get that. Numbers are just to explain what the argument says. The catch here in this particular question is the use of word "regularly" in the argument. Once we pay attention to that one, we're able to see the right answer/assumption more clearly :)

[RonPurewal]

Sure, Ron. I get that. Numbers are just to explain what the argument says. The catch here in this particular question is the use of word "regularly" in the argument. Once we pay attention to that one, we're able to see the right answer/assumption more clearly :)

Nope. "Regularly" isn't essential. If we change the argument to "drivers/vehicles who/that have ever broken the speed limit vs. drivers/vehicles receiving speeding tickets", the same issues obtain.

The essence of the problem is that the distribution of speeding tickets may or may not be representative of the drivers' speeding habits. The frequency/regularity of the speeding is immaterial.

(In fact, these 3 things"”"speed regularly", "speed ever", and "receive speeding ticket""”are all substantially different. So, for instance, one could create another problem, much like this one, that turns on the distinction of "speed regularly vs. have ever sped" rather than on tickets vs. speeding.)

[divineacclivity]

Sure, Ron. I get that. Numbers are just to explain what the argument says. The catch here in this particular question is the use of word "regularly" in the argument. Once we pay attention to that one, we're able to see the right answer/assumption more clearly :)

Nope. "Regularly" isn't essential. If we change the argument to "drivers/vehicles who/that have ever broken the speed limit vs. drivers/vehicles receiving speeding tickets", the same issues obtain.

The essence of the problem is that the distribution of speeding tickets may or may not be representative of the drivers' speeding habits. The frequency/regularity of the speeding is immaterial.

(In fact, these 3 things"”"speed regularly", "speed ever", and "receive speeding ticket""”are all substantially different. So, for instance, one could create another problem, much like this one, that turns on the distinction of "speed regularly vs. have ever sped" rather than on tickets vs. speeding.)

Ron,

Thank you very much for making me understand the right point of view.
I get confused everytime I read this problem after a gap of a few days. Ron, please see if I understand the question/argument correctly.
----------------------
My understanding:
- 3%of vehicles have radar detectors
- of the ticketed vehicles, 33% were radar-fitted
Author's conclusion: Radar-fitted vehicles must be over-speeding more frequently/regularly than non-radar vehicles.

=> assumption would've been: regular speed-limit offenders get ticketed more easily/more often than occasional (less regular) offenders

and this is what option B states probably.

Firstly, Is my understanding right?
-----------------------

(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.
Secondly, to me, option B could mean either of the following:
(i) Ticketed drivers over-speed more than non-ticketed as if drivers don't care about speed limit after receiving a ticket for over-speeding
i.e. in this sense, it doesn't mean: ticketing happened for regularly speeding rather it means: ticketing caused them to over-speed
(ii) The intended meaning as per the argument:
Regular speed-limit offenders get ticketed more easily/frequently than non-regular offenders. For this meaning, I'd probably write something like this:
Drivers who are ticketed for exceeding the speed limit are the ones who exceed the speed limit more regularly than ...

I'm sure my interpretation of the sentence (option B) must be wrong because this option is the right answer choice and no one else seems to have pointed out this meaning of the sentence but Ron, it'd really help me a lot if you could help me understand why this meaning has been incorrectly interpreted and how differently the sentence would be written if it had to convey this kind of a meaning.

[RonPurewal]

My understanding:
- 3%of vehicles have radar detectors
- of the ticketed vehicles, 33% were radar-fitted
Author's conclusion: Radar-fitted vehicles must be over-speeding more frequently/regularly than non-radar vehicles.

=> assumption would've been: regular speed-limit offenders get ticketed more easily/more often than occasional (less regular) offenders

and this is what option B states probably.

Firstly, Is my understanding right?

Basically yes.

If you're still confused, make it even simpler. A good start is to get rid of the specific numbers.

"- Radar detectors are present uncommonly often in cars pulled over for speeding.
- So... radar detectors must be present uncommonly often in cars driven over the speed limit.

There. That's a précis of the entire argument. The whole thing.

The point is that they're just assuming a connection between the two boldface things.

[RonPurewal]

Secondly, to me, option B could mean either of the following:
(i) Ticketed drivers over-speed more than non-ticketed as if drivers don't care about speed limit after receiving a ticket for over-speeding
i.e. in this sense, it doesn't mean: ticketing happened for regularly speeding rather it means: ticketing caused them to over-speed
(ii) The intended meaning as per the argument:
Regular speed-limit offenders get ticketed more easily/frequently than non-regular offenders. For this meaning, I'd probably write something like this:

Common sense dictates that you should ignore (i), because it is preposterous. That's not how things work in the real world. (If getting a ticket is going to affect people's behavior in any way... it's going to make them slow down!)

[divineacclivity]

My understanding:
- 3%of vehicles have radar detectors
- of the ticketed vehicles, 33% were radar-fitted
Author's conclusion: Radar-fitted vehicles must be over-speeding more frequently/regularly than non-radar vehicles.

=> assumption would've been: regular speed-limit offenders get ticketed more easily/more often than occasional (less regular) offenders

and this is what option B states probably.

Firstly, Is my understanding right?

Basically yes.

If you're still confused, make it even simpler. A good start is to get rid of the specific numbers.

"- Radar detectors are present uncommonly often in cars pulled over for speeding.
- So... radar detectors must be present uncommonly often in cars driven over the speed limit.

There. That's a précis of the entire argument. The whole thing.

The point is that they're just assuming a connection between the two boldface things.

Ok, Ron. thank you very much.

[divineacclivity]

Secondly, to me, option B could mean either of the following:
(i) Ticketed drivers over-speed more than non-ticketed as if drivers don't care about speed limit after receiving a ticket for over-speeding
i.e. in this sense, it doesn't mean: ticketing happened for regularly speeding rather it means: ticketing caused them to over-speed
(ii) The intended meaning as per the argument:
Regular speed-limit offenders get ticketed more easily/frequently than non-regular offenders. For this meaning, I'd probably write something like this:

Common sense dictates that you should ignore (i), because it is preposterous. That's not how things work in the real world. (If getting a ticket is going to affect people's behavior in any way... it's going to make them slow down!)

I got your point; thank you very much Ron.

[RonPurewal]

You're welcome.