• e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors

Video 38 Of RC Module

This topic has 1 expert reply and 1 member reply
javzprobz Junior | Next Rank: 30 Posts Default Avatar
Joined
22 Jul 2012
Posted:
16 messages
Thanked:
2 times
Target GMAT Score:
700+

Video 38 Of RC Module

Post Sun Jul 14, 2013 6:39 am
Hi Brent!

I have a quick question regarding the video 38 of RC module. The video is a RC question about cyclists. I think I really understand the somehow quantitative logic that we need in order to solve the question (I'm talking about the part that you explain the scenarios for cyclists involved in accidents and victims). Even though that I picked a wrong answer choice while solving the question on my own, I absolutely understood the question after your explanation. However,I wonder how you got to "less than 80% of cyclists in accidents were not wearing helmet" assumption. Yes, I understand that since 80% of the victims were not wearing helmet, the lower percentage of cyclists who were not wearing helmets in accidents we'd have, the better our conclusion would sound. So the part that I understand is that if out of 10,000 cyclists involved in accidents last year 8000 did not wear helmets, since 800 who died did not wear helmet, we would have 800/8000 (10%). If out of 10,000 cyclists involved in accidents last year 2000 did not wear helmets, we would have 800/2000 (40%). So the higher this percentage, the more logical our conclusion. However, I feel like if the answer choice C had said less than 70 or 60% (which is OK with your assumption since they are less than 80%), I would have not picked it. I feel like that our assumption should have mentioned less than 50%, not 80% (so only if C had said 10,20,30,40, or less than 50% I would have picked it (I know that C says 20% and that's why it is the answer).

I don't know if my question is clear. I would appreciate it if you enlighten me. Thanks a lot in advance.

Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
Post Sun Jul 14, 2013 7:17 am
Good question, javzprobz.

First of all, this is a VERY difficult CR question.

I'd like to answer your question with an example that's analogous to the helmet example.

Let's say that a study looked at all murders in the U.S. in 2012 and found that 80% of the murderers were right-handed.
Can we conclude that being right-handed increases one's likelihood of becoming a murderer? The answer depends on the proportion of right-handed people in the general population.
If it were the case that 80% of all people are right-handed, then it makes perfect sense that 80% of the murderers were right-handed. Here, the proportion of right-handed murderers is the same as the proportion of right-handed people in the general public. So, there's no connection between right-handedness and becoming a murderer.
However, If it were the case that 50% of all people are right-handed, then we'd expect the proportion of right-handed murderers to be about 50%. So, if the 80% of the murderers were right-handed, then we might conclude that there's a connection between right-handedness and one's potential for murder.
So, if 50% of people in the general public are right-handed, then our conclusion is very convincing.
If 5% of people in the general public are right-handed, then our conclusion is even more convincing.
If 60% of people in the general public are right-handed, then our conclusion is less convincing.

So, as you suggest, answer choice C would have been much more compelling if the percent were really low (like 10%). However, we're not trying to find an answer choice that guarantees the conclusion. We're just looking for an answer choice that strengthens the conclusion.

Since answer choice C is the only option that strengthens the conclusion, it must be the correct answer.

I hope that helps.

Cheers,
Brent

_________________
Brent Hanneson – Founder of GMATPrepNow.com
Use our video course along with Beat The GMAT's free 60-Day Study Guide

Check out the online reviews of our course
Come see all of our free resources

Thanked by: javzprobz
GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!
javzprobz Junior | Next Rank: 30 Posts Default Avatar
Joined
22 Jul 2012
Posted:
16 messages
Thanked:
2 times
Target GMAT Score:
700+
Post Sun Jul 21, 2013 8:08 am
Got it. Thank you so much.

Best Conversation Starters

1 LUANDATO 116 topics
2 lheiannie07 88 topics
3 AAPL 80 topics
4 Roland2rule 79 topics
5 swerve 71 topics
See More Top Beat The GMAT Members...

Most Active Experts

1 image description EconomistGMATTutor

The Economist GMAT Tutor

170 posts
2 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

120 posts
3 image description Rich.C@EMPOWERgma...

EMPOWERgmat

119 posts
4 image description GMATGuruNY

The Princeton Review Teacher

114 posts
5 image description Jay@ManhattanReview

Manhattan Review

106 posts
See More Top Beat The GMAT Experts