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 Your Progress

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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jun 2010, 09:31

1

This post received KUDOS

14

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

55% (hard)

Question Stats:

64% (02:41) correct
36% (01:33) wrong based on 381 sessions

HideShow timer Statistics

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?

then 10% exceed/ticketed = 10 20% exceed/not ticketed = 20

since they were either ticketed or not ticketed, all options have been covered; you have 30 total people that have exceeded the speed limit. This is 30% of 100.

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};

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 1/2% b)12 1/2% c)15% d)22% e)30%

z= total motorists y=motorists who speed and dont get ticket = y motorists who speed = x =.1z+y We are told that .2x=y

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 _________________

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 1/2% b)12 1/2% c)15% d)22% e)30%

Let's assume total # of motorists to be 100.

{# 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};

\(10+0.2x=x\) --> \(x=12.5\).

Answer: B.

Hope it's clear.

i dont understand why cant it be 20 + 0.1 x = x??

as in how do we know we pick 10 for 10% of people who exceeded speed and received tickets and not equate it to 0.1 x = # of people who received tickets ???

we have taken 0.2 x as no. of people who speeded but dd not receive tickets ... so we should have similarly done for 10% of people who exceeded speed and received tickets which is 0.1 x but bunnels explanation just picks a number 10 so i am confused

Kostyan5 can you please explain in detail how did you get to your answer?

If 20% of the motorist who exceeded the speed limit did not get a ticket, then 80% of the motorist who exceeded the speed limit got a ticket. We are also told that 10% of all motorist exceed the limit and get tickets. So 10% of all motorists and 80% of motorist who exceeded the limit refer to the same group of people (exceeded and were ticketed).

\(10% = 80% * motorist who exceeded\) \(motorists who exceeded = \frac{10}{80} =.125 or 12.5%\)

Re: On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jul 2013, 02:11

chintzzz wrote:

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%

This is an overlapping set question

Given 10 percent of motorists exceed speed limit and receive tickets

Receive Tickets don't receive tickets

Exceed 10 20/100X X

Don't Exceed

Let the total number for those who exceed be X then 20 percent of those received no tickets

When we solve we get 10 + \(\frac{20}{100 X}\) = X

Re: On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jul 2013, 05:15

Sorry for offtop- Can you please tell me whether you also edit the level of questions? I mean this question is marked as 700level, but I have some doubts about that. could you please also give me a link to Suggestions topic? I have some ideas. _________________

Happy are those who dream dreams and are ready to pay the price to make them come true

I am still on all gmat forums. msg me if you want to ask me smth

Re: On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jul 2013, 06:14

Expert's post

LalaB wrote:

Sorry for offtop- Can you please tell me whether you also edit the level of questions? I mean this question is marked as 700level, but I have some doubts about that. could you please also give me a link to Suggestions topic? I have some ideas.

Difficulty level is somewhat subjective, notice though that 45% of the users answered the question incorrectly. What would you say the difficulty level of this question should be? _________________

Re: On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jul 2013, 08:22

Imho it is 600 level I have read once that 700level question is the one that needs at least 2 steps to be solved or the one that covers hard topics like combinatorics etc

Actually i didnt mean anything bad. I am not a math guru at all (unfortunately hehe) and have no right to judge a question. All i want to know is that whether you Bunuel edit that "level" tag. I rely on ur experience. But sometimes i get confused by these tags and just wonder what you think and whether u pay attention to the tags Ok, now i know that u edit these tags too. Thnx for the information _________________

Happy are those who dream dreams and are ready to pay the price to make them come true

I am still on all gmat forums. msg me if you want to ask me smth

Re: On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jul 2013, 08:34

1

This post received KUDOS

Expert's post

LalaB wrote:

Imho it is 600 level I have read once that 700level question is the one that needs at least 2 steps to be solved or the one that covers hard topics like combinatorics etc

Actually i didnt mean anything bad. I am not a math guru at all (unfortunately hehe) and have no right to judge a question. All i want to know is that whether you Bunuel edit that "level" tag. I rely on ur experience. But sometimes i get confused by these tags and just wonder what you think and whether u pay attention to the tags Ok, now i know that u edit these tags too. Thnx for the information

Actually you have the same right to judge as anyone else. In fact you can change the difficulty tag (or any other tag for that matter) if you strongly feel that it's not correct. As for this question, I concur, it's not 700 level, though let's wait some time and see how the stats change.

P.S. Yes, I do pay attention to the tags and permanently review them. _________________

Re: On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jul 2013, 08:46

Bunuel, thanks for ur kind reply. Could u plz send me a link to the suggestion topic? As a user I have some minor suggestions.i tried to find that topic _________________

Happy are those who dream dreams and are ready to pay the price to make them come true

I am still on all gmat forums. msg me if you want to ask me smth

Re: On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jul 2013, 08:52

Expert's post

LalaB wrote:

Bunuel, thanks for ur kind reply. Could u plz send me a link to the suggestion topic? As a user I have some minor suggestions.i tried to find that topic

Re: On a certain road 10% of the motorists exceed the posted spe [#permalink]

Show Tags

16 Jul 2013, 21:10

2

This post received KUDOS

Expert's post

LalaB wrote:

I have read once that 700level question is the one that needs at least 2 steps to be solved or the one that covers hard topics like combinatorics etc

I would like to give my opinion on this statement:

Let's think about how the GMAT software decides the level of a question (simplifying the process by saying that it allots a level number to each question instead of a difficulty graph). The difficulty level is assigned by the people who take the test and not by the question setters.

You have experimental questions, right? They are there to estimate the difficulty level (among other things) of the new question. Say, most test takers spend 3-4 mins on a particular question and still get it wrong. The software is likely to assign it a high difficulty level. It doesn't matter how many steps it needed or the topic it tested. Some of the most tricky questions are from number properties which I think is extremely simple theoretically.

So what defines the difficulty level? The perception of the people. Why are combinatorics questions usually considered hard? Because people assume they are hard - they could be extremely straight forward but the moment people see 'how many ways' or 'what is the probability', they tend to take a step back. Similarly, function questions are usually considered difficult because of the notation but if you get over that notation you will see that those questions are usually very simple with a step wise process. Also, the answer to a question may be apparent to you with no steps needed if you understand the basics very well. To many others, it might seem very tricky and they might work on it for 5 mins before arriving at the solution. Therefore, when you think about the level of a question, think of how people will perceive it (hard to do without any data and/or experience in this field) rather than what you feel about the question. You may be very good at a topic and hence may feel that a certain question is simple but many others may not share your opinion. At the end of the day, opinion of the masses is what decides the question level (which implies a huge opportunity to do well by being comfortable in questions people consider hard). _________________

Part 2 of the GMAT: How I tackled the GMAT and improved a disappointing score Apologies for the month gap. I went on vacation and had to finish up a...

I’m a little delirious because I’m a little sleep deprived. But whatever. I have to write this post because... I’M IN! Funnily enough, I actually missed the acceptance phone...

So the last couple of weeks have seen a flurry of discussion in our MBA class Whatsapp group around Brexit, the referendum and currency exchange. Most of us believed...

This highly influential bestseller was first published over 25 years ago. I had wanted to read this book for a long time and I finally got around to it...