78. 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.
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
Driver's report-OG
This topic has expert replies
-
bhumika.k.shah
- Legendary Member
- Posts: 941
- Joined: Sun Dec 27, 2009 12:28 am
- Thanked: 20 times
- Followed by:1 members
-
komal
- Legendary Member
- Posts: 777
- Joined: Fri Jan 01, 2010 4:02 am
- Location: Mumbai, India
- Thanked: 117 times
- Followed by:47 members
bhumika.k.shah wrote:78. 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.
Incorrect : This paraphrases one of the premises. Hence eliminated.
(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.
Correct: To reach the conclusion, it must be assumed that these ticketed drivers exceed the speed limit on a regular basis.
(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.
Incorrect : The report is based on percentages of drivers with detectors and drivers who were ticketed. This answer choice is clearly Number v/s Percentage trap. Eliminated !
(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.
Incorrect : Whether the drivers were ticketed once or more than once is irrelevant.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
Incorrect : Comparison between drivers on maryland highway drivers with drivers on other highways is irrelevant to the scope of the argument
Hope this helps : )
-
melguy
- Master | Next Rank: 500 Posts
- Posts: 335
- Joined: Mon Mar 21, 2011 11:31 pm
- Location: Australia / India
- Thanked: 37 times
- Followed by:2 members
I had between B and C but could not find the reason to eliminate C. So thanks for pointing out the mistake.komal wrote:bhumika.k.shah wrote:78. 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.
Incorrect : This paraphrases one of the premises. Hence eliminated.
(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.
Correct: To reach the conclusion, it must be assumed that these ticketed drivers exceed the speed limit on a regular basis.
(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.
Incorrect : The report is based on percentages of drivers with detectors and drivers who were ticketed. This answer choice is clearly Number v/s Percentage trap. Eliminated !
(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.
Incorrect : Whether the drivers were ticketed once or more than once is irrelevant.
(E) Drivers on Maryland highways exceeded the speed limit more often than did drivers on other state highways not covered in the report.
Incorrect : Comparison between drivers on maryland highway drivers with drivers on other highways is irrelevant to the scope of the argument
Hope this helps : )
One thing i still do not get it is the link between the radar detector and the high frequency of the tickets issued.
Thanks
-
GmatVerbal
- Master | Next Rank: 500 Posts
- Posts: 138
- Joined: Thu Nov 12, 2009 10:07 am
- Thanked: 19 times
- Followed by:3 members
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.
drivers who equip their vehicles with radar detectors (DR) = { drivers who equip their vehicles with radar detectors and also got ticketed - DRT} + {drivers who equip their vehicles with radar detectors and who are not ticketed - DRNT}
the conclusion is DR exceeds regularly than drivers who don't have radar detectors ==>
DRT ( which is a subset) regularly than drivers who don't have radar detectors; --> this is the assumption.
The characteristic is true for a set ==> true of subset;
interestingly, those people in the DRNT who exceed speed limit regularly become members of DRT ( get ticketed one day);
i.e. DR who exceed speed limit regularly is same as = DRT;
A much simpler way to think the problem is to setup the reasoning chain:
33% of the ticketed drivers have radar detectors ===(1)===> drivers with radar detectors regularly exceed speed limit;
Huge logic gap in the reasoning to establish the link(1);
33% of the ticketed drivers have radar detectors ==> these people exceed speed limit regularly (assumption)==> drivers with radar detectors exceed speed regularly;
problem with choice(D):
3% of Maryland drivers with Radar detectors could be == 300000000;
33% of the ticketed vehicles could be just 300;
drivers who equip their vehicles with radar detectors (DR) = { drivers who equip their vehicles with radar detectors and also got ticketed - DRT} + {drivers who equip their vehicles with radar detectors and who are not ticketed - DRNT}
the conclusion is DR exceeds regularly than drivers who don't have radar detectors ==>
DRT ( which is a subset) regularly than drivers who don't have radar detectors; --> this is the assumption.
The characteristic is true for a set ==> true of subset;
interestingly, those people in the DRNT who exceed speed limit regularly become members of DRT ( get ticketed one day);
i.e. DR who exceed speed limit regularly is same as = DRT;
A much simpler way to think the problem is to setup the reasoning chain:
33% of the ticketed drivers have radar detectors ===(1)===> drivers with radar detectors regularly exceed speed limit;
Huge logic gap in the reasoning to establish the link(1);
33% of the ticketed drivers have radar detectors ==> these people exceed speed limit regularly (assumption)==> drivers with radar detectors exceed speed regularly;
problem with choice(D):
3% of Maryland drivers with Radar detectors could be == 300000000;
33% of the ticketed vehicles could be just 300;
