Last visit was: 20 Sep 2024, 11:11 It is currently 20 Sep 2024, 11:11
Toolkit
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

# On a certain road 10% of the motorists exceed the posted speed limit

SORT BY:
Tags:
Show Tags
Hide Tags
Joined: 11 Aug 2020
Posts: 1236
Own Kudos [?]: 216 [0]
Given Kudos: 332
Joined: 11 Dec 2019
Posts: 66
Own Kudos [?]: 53 [2]
Given Kudos: 117
Location: India
Concentration: Technology
GPA: 4
GMAT Club Legend
Joined: 19 Dec 2014
Status:GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Posts: 21832
Own Kudos [?]: 11885 [1]
Given Kudos: 450
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Joined: 15 Dec 2016
Posts: 1315
Own Kudos [?]: 233 [0]
Given Kudos: 188
Re: On a certain road 10% of the motorists exceed the posted speed limit [#permalink]
Bunuel
chintzzz
On a certain road 10% of the motorists exceed the posted speed limit and receive speeding tickets, but 20% of the motorists who exceed the posted speed limit do not receive speeding tickets. What percent of the motorists on the road exceed the posted speed limit?

A. 10.5%
B. 12.5%
C. 15%
D. 22%
E. 30%

Say there are 100 motorists.

{# of motorists who exceed speed & receive tickets} + {# of motorists who exceed speed & don't receive tickets} = {Total # of motorist who exceed speed};

Given: {# of motorists who exceed speed & receive tickets}=10;

Also, if {Total # of motorist who exceed speed}=x, then 0.2x={# of motorists who exceed speed & don't receive tickets};

$$10+0.2x=x$$ --> $$x=12.5$$.

Hope it's clear.

Hi Bunuel - how can "X" (Which is Total # of motorist who exceed speed} ever by a non integer ?

We are talking about human beings here..

Do you find that strange ? I also got the 12.5 and I thought "hmmm something must be wrong here as we can't have 12.5 human beings"

Thoughts ?
Math Expert
Joined: 02 Sep 2009
Posts: 95690
Own Kudos [?]: 660592 [0]
Given Kudos: 87331
Re: On a certain road 10% of the motorists exceed the posted speed limit [#permalink]
jabhatta2
Bunuel
chintzzz
On a certain road 10% of the motorists exceed the posted speed limit and receive speeding tickets, but 20% of the motorists who exceed the posted speed limit do not receive speeding tickets. What percent of the motorists on the road exceed the posted speed limit?

A. 10.5%
B. 12.5%
C. 15%
D. 22%
E. 30%

Say there are 100 motorists.

{# of motorists who exceed speed & receive tickets} + {# of motorists who exceed speed & don't receive tickets} = {Total # of motorist who exceed speed};

Given: {# of motorists who exceed speed & receive tickets}=10;

Also, if {Total # of motorist who exceed speed}=x, then 0.2x={# of motorists who exceed speed & don't receive tickets};

$$10+0.2x=x$$ --> $$x=12.5$$.

Hope it's clear.

Hi Bunuel - how can "X" (Which is Total # of motorist who exceed speed} ever by a non integer ?

We are talking about human beings here..

Do you find that strange ? I also got the 12.5 and I thought "hmmm something must be wrong here as we can't have 12.5 human beings"

Thoughts ?

We assumed that there were 100 motorists. So, basically we took the total number of motorists as 100%, so x = 12.5 is the percentage of motorist who exceed speed.
GMAT Club Legend
Joined: 08 Jul 2010
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Posts: 6063
Own Kudos [?]: 14160 [0]
Given Kudos: 125
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Re: On a certain road 10% of the motorists exceed the posted speed limit [#permalink]
chintzzz
On a certain road 10% of the motorists exceed the posted speed limit and receive speeding tickets, but 20% of the motorists who exceed the posted speed limit do not receive speeding tickets. What percent of the motorists on the road exceed the posted speed limit?

A. 10.5%
B. 12.5%
C. 15%
D. 22%
E. 30%

Video solution by GMATinsight

Get TOPICWISE: Concept Videos | Practice Qns 100+ | Official Qns 50+ | 100% Video solution CLICK HERE.
Two MUST join YouTube channels : GMATinsight (1000+ FREE Videos) and GMATclub
Joined: 31 Mar 2022
Posts: 11
Own Kudos [?]: 2 [0]
Given Kudos: 26
Location: India
Concentration: General Management, Entrepreneurship
GPA: 3.4
Re: On a certain road 10% of the motorists exceed the posted speed limit [#permalink]
This is one of those Questions where you feel pissed because of the language of the question. My threshold for dealing with such questions is minimal. Thus, I am going to leave this one
Joined: 24 Dec 2022
Posts: 273
Own Kudos [?]: 149 [0]
Given Kudos: 222
On a certain road 10% of the motorists exceed the posted speed limit [#permalink]
KarishmaB
On a certain road, 10 percent of the motorists exceed the posted speed limit and receive speeding tickets, but 20% of the motorists who exceed the posted speed limit do not receive speeding tickets. What percent of the motorists on that road exceed the posted speed limit?

A/ 10 1/2%
B/ 12 1/2%
C/ 15%
D/ 22%
E/ 30%

Read one line at a time and analyze it.

On a certain road, 10 percent of the motorists exceed the posted speed limit and receive speeding tickets,

>>>>10% of total motorists exceed speed limit and get tickets

but 20% of the motorists who exceed the posted speed limit do not receive speeding tickets.

>>>>>>20% who exceed the speed limit do not get tickets. Then 80% who exceed the speed limit must be getting tickets.

What percent of the motorists on that road exceed the posted speed limit?

>>>>> So 10% of total motorists = 80% of those who exceed speed limit
So those who exceed speed limits are 1/8 = 12.5% of the motorists
Oh my god Karishma! You are truly a genius! My mind is blown.
On Quant, you singlehandedly blow all the other so called "Experts" out of the water.
Just amazing.
Thanks for such great work.
Joined: 05 Mar 2024
Posts: 156
Own Kudos [?]: 31 [0]
Given Kudos: 7
Re: On a certain road 10% of the motorists exceed the posted speed limit [#permalink]
gmat1220
Using double matrix.
­Why is the 20% done as 0.2 while the 10% is left as it is. Shouldn't it be 0.1 as well?!
Re: On a certain road 10% of the motorists exceed the posted speed limit [#permalink]
1   2
Moderator:
Math Expert
95690 posts