Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 21 Oct 2016, 09:48

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# m12#11 - Number System

Author Message
Director
Joined: 25 Aug 2007
Posts: 954
WE 1: 3.5 yrs IT
WE 2: 2.5 yrs Retail chain
Followers: 74

Kudos [?]: 1216 [0], given: 40

### Show Tags

12 Jun 2010, 06:01
If each year the population of the country grows by 20%, how many years will elapse before the population of the country doubles?

A) 3
B) 4
C) 5
D) 6
E) 7

OA is B and OE is:
Let the starting population be X. There will be change in population by a factor of $$\frac{6}{5}$$ every year. So, in 4 years the population becomes:
$$(\frac{6}{5})^{4x}$$ = 2.0736X

So, after 4 yrs, population become >double X.

I have a doubt: The population becomes double before the completion of 4th yr. So, it mean 3 yrs are passed not 4.

_________________

Tricky Quant problems: http://gmatclub.com/forum/50-tricky-questions-92834.html
Important Grammer Fundamentals: http://gmatclub.com/forum/key-fundamentals-of-grammer-our-crucial-learnings-on-sc-93659.html

Manager
Joined: 21 Feb 2010
Posts: 212
Followers: 1

Kudos [?]: 24 [0], given: 1

Re: m12#11 - Number System [#permalink]

### Show Tags

12 Jun 2010, 06:18
there is no such answer as 3.5,...instead, there are integers. it takes more than 3 years to double the population, therefore, it takes approximately 4 years to double it.
Director
Joined: 25 Aug 2007
Posts: 954
WE 1: 3.5 yrs IT
WE 2: 2.5 yrs Retail chain
Followers: 74

Kudos [?]: 1216 [0], given: 40

Re: m12#11 - Number System [#permalink]

### Show Tags

12 Jun 2010, 06:39
I think you misread the question stem:
If each year the population of the country grows by 20%, how many years will elapse before the population of the country doubles?

I think before completion of 4th yr, population gets doubled. So, 3 yr elapsed.
_________________

Tricky Quant problems: http://gmatclub.com/forum/50-tricky-questions-92834.html
Important Grammer Fundamentals: http://gmatclub.com/forum/key-fundamentals-of-grammer-our-crucial-learnings-on-sc-93659.html

Manager
Joined: 01 Mar 2009
Posts: 194
Location: United States
Concentration: Strategy, Technology
GMAT 1: 660 Q47 V34
GMAT 2: 680 Q46 V38
GPA: 3.2
WE: Consulting (Computer Software)
Followers: 3

Kudos [?]: 42 [0], given: 23

Re: m12#11 - Number System [#permalink]

### Show Tags

17 Apr 2011, 15:47
I know its been a while since someone has talked about this problem, but I agree with the author of this post. The population is doubled before the completion of the 4th year, so the answer should be 3.
Director
Status: Verbal Forum Moderator
Joined: 17 Apr 2013
Posts: 635
Location: India
GMAT 1: 710 Q50 V36
GMAT 2: 750 Q51 V41
GMAT 3: 790 Q51 V49
GPA: 3.3
Followers: 57

Kudos [?]: 374 [0], given: 297

Re: m12#11 - Number System [#permalink]

### Show Tags

25 Apr 2014, 21:18
ykaiim wrote:
If each year the population of the country grows by 20%, how many years will elapse before the population of the country doubles?

A) 3
B) 4
C) 5
D) 6
E) 7

OA is B and OE is:
Let the starting population be X. There will be change in population by a factor of $$\frac{6}{5}$$ every year. So, in 4 years the population becomes:
$$(\frac{6}{5})^{4x}$$ = 2.0736X

So, after 4 yrs, population become >double X.

I have a doubt: The population becomes double before the completion of 4th yr. So, it mean 3 yrs are passed not 4.

Bunuel i also believe that the correct answer is 3 because it is not taking full 4 years, approx 3 years 10 months.
_________________

Like my post Send me a Kudos It is a Good manner.
My Debrief: http://gmatclub.com/forum/how-to-score-750-and-750-i-moved-from-710-to-189016.html

Re: m12#11 - Number System   [#permalink] 25 Apr 2014, 21:18
Similar topics Replies Last post
Similar
Topics:
2 Number System- Divisibility 2 26 Jun 2010, 02:18
m12#23 - Number System 5 12 Jun 2010, 06:24
2 Number Properties 4 21 Jan 2010, 14:03
Number Properties 2 16 Jan 2010, 03:03
M13 System Issue 1 12 Aug 2008, 19:22
Display posts from previous: Sort by

# m12#11 - Number System

Moderator: Bunuel

 Powered by phpBB © phpBB Group and phpBB SEO Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.