Motorcycle safety classes.

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Motorcycle safety classes.

by lukaswelker » Thu Apr 17, 2014 9:50 am
Hey Guys

I can't see the reasoning behind the following,

Motorcycle-safety courses, offered by a number of organizations, teach motorcyclists important techniques for handling and for safely sharing the road with other road users. If more motorcyclists took these courses, there would be fewer serious motorcycle accidents. Data show that 92% of the motorcyclists who are involved in a serious motorcycle accident have never taken a motorcycle-safety course.

In assessing whether the data cited provided support for the position taken about motorcyclists' taking the courses, it would be most useful to determine which of the following?

- Whether significantly more than eight percent of motorcyclists have taken a motorcycle-safety course
- Whether it is riskier for a motorcyclist to ride with a passenger behind the rider than to ride alone
- Whether the different organizations that offer motorcycle-safety courses differ in the content of the courses that they offer
- Whether more than 92% of serious motorcycle accidents involve collisions between a motorcycle and another vehicle in motion.
- Whether variations in the size and potential speed of a motorcycle influence the risk of a serious accident's occuring.

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by theCodeToGMAT » Mon Apr 21, 2014 10:43 pm
Is the answer [spoiler]{A}[/spoiler]?

Fact says that:
"¢ 92% ppl have never taken courses
"¢ 8% did had courses..

Now to check the effectiveness of the claim that courses are usefull.. we need to have a statistics which shows that more people took the courses and some of them met accident. This is exactly what [spoiler]{A}[/spoiler] says.

What is the OA?
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by [email protected] » Mon Apr 21, 2014 11:34 pm
Hi lukaswelker,

The concept of "ratios" is tested a number of different times (and in a number of different ways) in the Quant section. It does sometimes show up in the Verbal section as well (and when it shows up there, it's usually in a CR prompt).

Here's what you need to notice about this CR prompt:

**92% of motorcyclists INVOLVED IN A SERIOUS ACCIDENT have never taken a safety course**

This implies a couple of things:
1) 8% of motorcyclists involved in a serious accident have taken a safety course.
2) There are motorcyclists who have NEVER been in a serious accident.

It's the second point that's worth the most attention. Some motorcyclists get in a serious accident, some don't - but we don't know how many of each there are. To properly assess the argument, we need to know about ALL motorcyclists, not just the ones who are in serious accidents. The argument doesn't really "hold up" if the number of motorcyclists in a serious accident is a really tiny number relative to ALL motorcyclists. The 92% ratio for serious accidents sets the "upper bar" for all motorcyclists. If more than 8% of ALL motorcyclists took a safety course, then the argument becomes less and less convincing (as the % who took a course increases, the "point" of the prompt becomes less meaningful).

The only answer that addresses this issue is A.

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by GMATGuruNY » Tue Apr 22, 2014 6:04 am
lukaswelker wrote:Hey Guys

I can't see the reasoning behind the following,

Motorcycle-safety courses, offered by a number of organizations, teach motorcyclists important techniques for handling and for safely sharing the road with other road users. If more motorcyclists took these courses, there would be fewer serious motorcycle accidents. Data show that 92% of the motorcyclists who are involved in a serious motorcycle accident have never taken a motorcycle-safety course.

In assessing whether the data cited provided support for the position taken about motorcyclists' taking the courses, it would be most useful to determine which of the following?

- Whether significantly more than eight percent of motorcyclists have taken a motorcycle-safety course
- Whether it is riskier for a motorcyclist to ride with a passenger behind the rider than to ride alone
- Whether the different organizations that offer motorcycle-safety courses differ in the content of the courses that they offer
- Whether more than 92% of serious motorcycle accidents involve collisions between a motorcycle and another vehicle in motion.
- Whether variations in the size and potential speed of a motorcycle influence the risk of a serious accident's occurring.
This is a SAMPLING argument.
Of cyclists involved in accidents, 92% did not take a safety course, implying that 8% DID take a safety course.
The passage offers statistics about SOME cyclists -- those involved in accidents -- and draws a conclusion about ALL cyclists.
Look for an answer choice that could make or break the link between SOME cyclists and ALL cyclists.

A: Whether significantly more than eight percent of [ALL] motorcyclists have taken a motorcycle-safety course
Test what happens if exactly 8% of all cyclists took a safety course.
To organize the data, we can use a double-matrix:

.............................Course..........No course............Total

Accident....................8.....................92..................100

No accident

Total.........................80...................920................1000

In the matrix above:
Of 1000 cyclists, exactly 8% took the course.
Of 100 accident victims, exactly 8% took the course.
Accident rate for course-takers = 8/80 = 10%.
Accident rate for non-course-takers = 92/920 = 10%.
The rate is the SAME in each case, weakening the conclusion that the course prevents accidents.
Thus, to conclude that the course prevents accidents, we need to know whether significantly more than eight percent of motorcyclists have taken a motorcycle-safety course.

The correct answer is A.
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by alanforde800Maximus » Tue Jun 12, 2018 8:00 am
GMATGuruNY wrote:
lukaswelker wrote:Hey Guys

I can't see the reasoning behind the following,

Motorcycle-safety courses, offered by a number of organizations, teach motorcyclists important techniques for handling and for safely sharing the road with other road users. If more motorcyclists took these courses, there would be fewer serious motorcycle accidents. Data show that 92% of the motorcyclists who are involved in a serious motorcycle accident have never taken a motorcycle-safety course.

In assessing whether the data cited provided support for the position taken about motorcyclists' taking the courses, it would be most useful to determine which of the following?

- Whether significantly more than eight percent of motorcyclists have taken a motorcycle-safety course
- Whether it is riskier for a motorcyclist to ride with a passenger behind the rider than to ride alone
- Whether the different organizations that offer motorcycle-safety courses differ in the content of the courses that they offer
- Whether more than 92% of serious motorcycle accidents involve collisions between a motorcycle and another vehicle in motion.
- Whether variations in the size and potential speed of a motorcycle influence the risk of a serious accident's occurring.
This is a SAMPLING argument.
Of cyclists involved in accidents, 92% did not take a safety course, implying that 8% DID take a safety course.
The passage offers statistics about SOME cyclists -- those involved in accidents -- and draws a conclusion about ALL cyclists.
Look for an answer choice that could make or break the link between SOME cyclists and ALL cyclists.

A: Whether significantly more than eight percent of [ALL] motorcyclists have taken a motorcycle-safety course
Test what happens if exactly 8% of all cyclists took a safety course.
To organize the data, we can use a double-matrix:

.............................Course..........No course............Total

Accident....................8.....................92..................100

No accident

Total.........................80...................920................1000

In the matrix above:
Of 1000 cyclists, exactly 8% took the course.
Of 100 accident victims, exactly 8% took the course.
Accident rate for course-takers = 8/80 = 10%.
Accident rate for non-course-takers = 92/920 = 10%.
The rate is the SAME in each case, weakening the conclusion that the course prevents accidents.
Thus, to conclude that the course prevents accidents, we need to know whether significantly more than eight percent of motorcyclists have taken a motorcycle-safety course.

The correct answer is A.
Hello Mitch,

Can you please explain why option D is incorrect?

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by Mo2men » Sat Sep 21, 2019 1:54 pm
GMATGuruNY wrote:
lukaswelker wrote:Hey Guys

I can't see the reasoning behind the following,

Motorcycle-safety courses, offered by a number of organizations, teach motorcyclists important techniques for handling and for safely sharing the road with other road users. If more motorcyclists took these courses, there would be fewer serious motorcycle accidents. Data show that 92% of the motorcyclists who are involved in a serious motorcycle accident have never taken a motorcycle-safety course.

In assessing whether the data cited provided support for the position taken about motorcyclists' taking the courses, it would be most useful to determine which of the following?

- Whether significantly more than eight percent of motorcyclists have taken a motorcycle-safety course
- Whether it is riskier for a motorcyclist to ride with a passenger behind the rider than to ride alone
- Whether the different organizations that offer motorcycle-safety courses differ in the content of the courses that they offer
- Whether more than 92% of serious motorcycle accidents involve collisions between a motorcycle and another vehicle in motion.
- Whether variations in the size and potential speed of a motorcycle influence the risk of a serious accident's occurring.
This is a SAMPLING argument.
Of cyclists involved in accidents, 92% did not take a safety course, implying that 8% DID take a safety course.
The passage offers statistics about SOME cyclists -- those involved in accidents -- and draws a conclusion about ALL cyclists.
Look for an answer choice that could make or break the link between SOME cyclists and ALL cyclists.

A: Whether significantly more than eight percent of [ALL] motorcyclists have taken a motorcycle-safety course
Test what happens if exactly 8% of all cyclists took a safety course.
To organize the data, we can use a double-matrix:

.............................Course..........No course............Total

Accident....................8.....................92..................100

No accident

Total.........................80...................920................1000

In the matrix above:
Of 1000 cyclists, exactly 8% took the course.
Of 100 accident victims, exactly 8% took the course.
Accident rate for course-takers = 8/80 = 10%.
Accident rate for non-course-takers = 92/920 = 10%.
The rate is the SAME in each case, weakening the conclusion that the course prevents accidents.
Thus, to conclude that the course prevents accidents, we need to know whether significantly more than eight percent of motorcyclists have taken a motorcycle-safety course.

The correct answer is A.
Hi GMATGuru,

1- What the word significant mean here in the OA? Do we consider 10% is acceptable here?

2- If the percentage is less than 8%, what would be the effect on the argument?

3- In some arguments the numbers are important, why here is the percentage important? i.e: in your example above, if we 8 out of 80 cases, then we still have have big numbers (72) took the courses without accidents, So how this is weakening the conclusion while we still have big number.

Can you elaborate please?

Thanks in advance

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by GMATGuruNY » Wed Oct 02, 2019 5:50 am
Hi GMATGuru,

1- What the word significant mean here in the OA? Do we consider 10% is acceptable here?
For course to be deemed effective, the accident rate for course-takers must be SIGNIFICANTLY LESS than that for non-course-takers.
2- If the percentage is less than 8%, what would be the effect on the argument?
.............................Course..........No course............Total

Accident....................8.....................92..................100

No accident

Total.........................10...................990................1000

In the matrix above:
Of 1000 cyclists, exactly 1% took the course.
Of 100 accident victims, exactly 8% took the course.
Accident rate for course-takers = 8/10 = 80%.
Accident rate for non-course-takers = 92/990 = less than 10%.
Here, the accident rate for course-takers is GREATER than that for non-course-takers, weakening the conclusion that the course prevents accidents.
Implication:
If the percentage of cyclists taking the course is 8% or less, the accident rate for course-takers is NOT less that that for non-course-takers, weakening the conclusion that the course is effective.
Thus -- to support the conclusion that the course is effective -- significantly MORE than eight percent of motorcyclists must have taken the course.
3- In some arguments the numbers are important, why here is the percentage important? i.e: in your example above, if we 8 out of 80 cases, then we still have have big numbers (72) took the courses without accidents, So how this is weakening the conclusion while we still have big number.
The course will lead to fewer serious accidents only if the course is effective.
The effectiveness of the course cannot be determined soley by the number of accidents.
If the total number of cyclists declines by 50%, then the number of accidents might also decline by 50%.
In this case, the decline in the number of accidents would be unrelated to the percentage of cyclists who took the course -- making it impossible to use the number of accidents to evaluate the effectiveness of the course.
To conclude that the course is effective, we need to know that the accident RATE for course-takers is significantly less than that for non-course-takers.
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