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:

Boomtown urban planners expect the city’s population to [#permalink]

Show Tags

03 Mar 2012, 13:57

1

This post received KUDOS

3

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

45% (medium)

Question Stats:

62% (02:39) correct
38% (01:27) wrong based on 173 sessions

HideShow timer Statistics

Boomtown urban planners expect the city’s population to increase by 10% per year over the next two years. If that projection were to come true, the population two years from now would be exactly double the population of one year ago. Which of the following is closest to the percent population increase in Boomtown over the last year?

A. 20% B. 40% C. 50% D. 65% E. 75%

This how I am trying to solve, but I am stuck after this.

If we assume that today’s population is 100, next year it would be 1.1 × 100 = 110, and the following year it would be 1.1 × 110 = 121. If this is double the population of one year ago, the population at that time must have been 0.5 × 121 = 60.5. Because the problem seeks the “closest” answer choice, we can round 60.5 to 60.

Will it be 121-60/60? But this doesn't give me the right answer. Please help.

Re: Boomtown urban planners expect the city’s population to [#permalink]

Show Tags

03 Mar 2012, 14:23

8

This post received KUDOS

Expert's post

enigma123 wrote:

Boomtown urban planners expect the city’s population to increase by 10% per year over the next two years. If that projection were to come true, the population two years from now would be exactly double the population of one year ago. Which of the following is closest to the percent population increase in Boomtown over the last year?

A. 20% B. 40% C. 50% D. 65% E. 75%

This how I am trying to solve, but I am stuck after this.

If we assume that today’s population is 100, next year it would be 1.1 × 100 = 110, and the following year it would be 1.1 × 110 = 121. If this is double the population of one year ago, the population at that time must have been 0.5 × 121 = 60.5. Because the problem seeks the “closest” answer choice, we can round 60.5 to 60.

Will it be 121-60/60? But this doesn't give me the right answer. Please help.

Population now - 100; Population one year from now - 110; Population two years from now - 121;

Since the population two years from now (121) is exactly double the population one year ago then the population one year ago was 121/2=60.5.

Now, the question asks about the population increase over the last year, so from 60.5 (last year) to 100 (now): percent increase=difference/original*100=(100-60.5)/60.5*100=39.5/60.5*100=~2/3*100=~65%.

Re: Boomtown urban planners expect the city’s population to [#permalink]

Show Tags

10 Apr 2014, 00:52

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________

Re: Boomtown urban planners expect the city’s population to [#permalink]

Show Tags

10 Apr 2014, 02:34

enigma123 wrote:

Boomtown urban planners expect the city’s population to increase by 10% per year over the next two years. If that projection were to come true, the population two years from now would be exactly double the population of one year ago. Which of the following is closest to the percent population increase in Boomtown over the last year?

A. 20% B. 40% C. 50% D. 65% E. 75%

This how I am trying to solve, but I am stuck after this.

If we assume that today’s population is 100, next year it would be 1.1 × 100 = 110, and the following year it would be 1.1 × 110 = 121. If this is double the population of one year ago, the population at that time must have been 0.5 × 121 = 60.5. Because the problem seeks the “closest” answer choice, we can round 60.5 to 60.

Will it be 121-60/60? But this doesn't give me the right answer. Please help.

You have the calculation correct till 60.5 but we need the percentage increase of 60.5 to 100.00 => (100 - 60.5)/60.5 = 65%. even if you round 60.5 to 60 you will reach the correct answer.

Re: Boomtown urban planners expect the city’s population to [#permalink]

Show Tags

19 Apr 2015, 02:13

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________

Re: Boomtown urban planners expect the city’s population to [#permalink]

Show Tags

11 Apr 2016, 06:46

Am I correct to say that if we write \(P*(\frac{11}{10})^2=2S\) where P=present population, S= start population, so 1 year ago. That gives \(S=\frac{121P}{200}\) but after this, how can we relate the S to P to solve the question? Does this make sense?..

Like writing \(S*\frac{x}{100}=P\) gives 160% what's wrong here?..

Re: Boomtown urban planners expect the city’s population to [#permalink]

Show Tags

23 May 2016, 19:54

While solving the question, I used hit and trial using some number sense. So I know since the number doubled after two years when compared to what was year ago. let us say year ago was 100. If I start with 50 then I get 150 in the current year, 165 the year after and 181.5 the second year after. This does not double.

If I use 75%, then I get 175 this year, 192.5 the next year and more than 200 the second year, the answer is in between - 65%.

gmatclubot

Re: Boomtown urban planners expect the city’s population to
[#permalink]
23 May 2016, 19:54

http://blog.ryandumlao.com/wp-content/uploads/2016/05/IMG_20130807_232118.jpg The GMAT is the biggest point of worry for most aspiring applicants, and with good reason. It’s another standardized test when most of us...

I recently returned from attending the London Business School Admits Weekend held last week. Let me just say upfront - for those who are planning to apply for the...