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

It is currently 01 Aug 2014, 20:39

Close

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
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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

A certain rabbit population quadruples every three years.

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
3 KUDOS received
Moderator
Moderator
User avatar
Joined: 02 Jul 2012
Posts: 1226
Location: India
Concentration: Strategy
GMAT 1: 740 Q49 V42
GPA: 3.8
WE: Engineering (Energy and Utilities)
Followers: 61

Kudos [?]: 639 [3] , given: 116

GMAT Tests User Premium Member
A certain rabbit population quadruples every three years. [#permalink] New post 11 Dec 2012, 22:06
3
This post received
KUDOS
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

100% (01:58) correct 0% (00:00) wrong based on 23 sessions
Going to have a go at Problem Solving.. My own question, so no official answer. Please provide your feedback on how you found the question to be and anyway that I can make it clearer.. :)

A certain rabbit population quadruples every three years. The population today is 81. Exactly six years from today, the entire population will be fed to a pack of wolves. If each wolf eats exactly 12 rabbits, how many wolves can be fed using this rabbit population?

A. 54
B. 81
C. 108
D. 216
E. 324

[Reveal] Spoiler:
My Answer is C

_________________

Did you find this post helpful?... Please let me know through the Kudos button.

Thanks To The Almighty - My GMAT Debrief

GMAT Reading Comprehension: 7 Most Common Passage Types

Expert Post
Verbal Forum Moderator
Verbal Forum Moderator
User avatar
Status: Preparing for the another shot...!
Joined: 03 Feb 2011
Posts: 1425
Location: India
Concentration: Finance, Marketing
GPA: 3.75
Followers: 126

Kudos [?]: 571 [0], given: 62

GMAT ToolKit User GMAT Tests User Premium Member
Re: A certain rabbit population quadruples every three years. [#permalink] New post 11 Dec 2012, 22:47
Expert's post
MacFauz wrote:
Going to have a go at Problem Solving.. My own question, so no official answer. Please provide your feedback on how you found the question to be and anyway that I can make it clearer.. :)

A certain rabbit population quadruples every three years. The population today is 81. Exactly six years from today, the entire population will be fed to a pack of wolves. If each wolf eats exactly 12 rabbits, how many wolves can be fed using this rabbit population?

A. 54
B. 81
C. 108
D. 216
E. 324

[Reveal] Spoiler:
My Answer is C


y(t)=y(0) * 4^[t/I]
where:
y(t)=population after given number of years.
y(0)=initial population
t=time
I=amount of the time for the quantity to double.
Putting the respective values, we get population after 6 years as 1296.
Divide this by the exact capacity of wolves, and we get 108 as the answer.

Logical method:
the population is quadrupling two times. So find the population as soon as it quadruples for the first time. Then multiply the result again by 4 to get the population after 6 years.
And then the same.

+1C.

Btw Macfauz, you may apply to GMAC. I am quite certain that within a year or two, you may be writing questions for future GMAT takers.
Good Luck.
_________________

Prepositional Phrases Clarified|Elimination of BEING| Absolute Phrases Clarified
Rules For Posting
www.Univ-Scholarships.com

Moderator
Moderator
User avatar
Joined: 02 Jul 2012
Posts: 1226
Location: India
Concentration: Strategy
GMAT 1: 740 Q49 V42
GPA: 3.8
WE: Engineering (Energy and Utilities)
Followers: 61

Kudos [?]: 639 [0], given: 116

GMAT Tests User Premium Member
Re: A certain rabbit population quadruples every three years. [#permalink] New post 11 Dec 2012, 22:58
Marcab wrote:
MacFauz wrote:
Going to have a go at Problem Solving.. My own question, so no official answer. Please provide your feedback on how you found the question to be and anyway that I can make it clearer.. :)

A certain rabbit population quadruples every three years. The population today is 81. Exactly six years from today, the entire population will be fed to a pack of wolves. If each wolf eats exactly 12 rabbits, how many wolves can be fed using this rabbit population?

A. 54
B. 81
C. 108
D. 216
E. 324

[Reveal] Spoiler:
My Answer is C


y(t)=y(0) * 4^[t/I]
where:
y(t)=population after given number of years.
y(0)=initial population
t=time
I=amount of the time for the quantity to double.
Putting the respective values, we get population after 6 years as 1296.
Divide this by the exact capacity of wolves, and we get 108 as the answer.

Logical method:
the population is quadrupling two times. So find the population as soon as it quadruples for the first time. Then multiply the result again by 4 to get the population after 6 years.
And then the same.

+1C.

Btw Macfauz, you may apply to GMAC. I am quite certain that within a year or two, you may be writing questions for future GMAT takers.
Good Luck.


Haha.. Thanks Marcab.. Hopefully will be able to come up with more questions here before I can do that.. :)

Btw.. For the question.. We can save some time on the multiplication by keeping the final population in the form

3^4 * 2^4. Dividing this by 12 we get : \frac{3^4 * 2^4}{2^2 * 3} = 3^3 * 2^2 = 108
_________________

Did you find this post helpful?... Please let me know through the Kudos button.

Thanks To The Almighty - My GMAT Debrief

GMAT Reading Comprehension: 7 Most Common Passage Types

Manager
Manager
User avatar
Joined: 04 Oct 2011
Posts: 225
Location: India
Concentration: Entrepreneurship, International Business
GMAT 1: 440 Q33 V13
GMAT 2: 0 Q0 V0
GPA: 3
Followers: 0

Kudos [?]: 25 [0], given: 44

Re: A certain rabbit population quadruples every three years. [#permalink] New post 10 Jan 2013, 19:08
Marcab wrote:
MacFauz wrote:
Going to have a go at Problem Solving.. My own question, so no official answer. Please provide your feedback on how you found the question to be and anyway that I can make it clearer.. :)

A certain rabbit population quadruples every three years. The population today is 81. Exactly six years from today, the entire population will be fed to a pack of wolves. If each wolf eats exactly 12 rabbits, how many wolves can be fed using this rabbit population?

A. 54
B. 81
C. 108
D. 216
E. 324

[Reveal] Spoiler:
My Answer is C


y(t)=y(0) * 4^[t/I]
where:
y(t)=population after given number of years.
y(0)=initial population
t=time
I=amount of the time for the quantity to double.
Putting the respective values, we get population after 6 years as 1296.
Divide this by the exact capacity of wolves, and we get 108 as the answer.

Logical method:
the population is quadrupling two times. So find the population as soon as it quadruples for the first time. Then multiply the result again by 4 to get the population after 6 years.
And then the same.

+1C.

Btw Macfauz, you may apply to GMAC. I am quite certain that within a year or two, you may be writing questions for future GMAT takers.
Good Luck.



Hi Marcab,

I solved this using logical method.
But i tried to figure out ur algebraic method ... i couldn't :oops:

y(t)=population after given number of years. (x)
y(0)=initial population (81)
t=time (6)
I=amount of the time for the quantity to double. (3)

i'm getting x= 81*2
_________________

GMAT - Practice, Patience, Persistence
Kudos if u like :)

Expert Post
Verbal Forum Moderator
Verbal Forum Moderator
User avatar
Status: Preparing for the another shot...!
Joined: 03 Feb 2011
Posts: 1425
Location: India
Concentration: Finance, Marketing
GPA: 3.75
Followers: 126

Kudos [?]: 571 [0], given: 62

GMAT ToolKit User GMAT Tests User Premium Member
Re: A certain rabbit population quadruples every three years. [#permalink] New post 10 Jan 2013, 21:06
Expert's post
Hii Shan.
If you are pretty comfortable with the logical method, then don't get confuse with this one. Anyways, here is the clarification of my method:
y(t)=y(0)*4^{t/I}

where y(t)= population after 6 years.
y(0)=current population=81
4- multiplying factor.( Since here its given that population is quadrupling, hence 4)
t-time duration given=6
I-time interval during which the population quadruples=3

The relation becomes:
y(t)=81*4^{6/3}
y(t)=81*4^2
y(t)=81*16 or 1296.

On dividing this by # of rabbits, you will get the # of wolves.

Hope that helps.
_________________

Prepositional Phrases Clarified|Elimination of BEING| Absolute Phrases Clarified
Rules For Posting
www.Univ-Scholarships.com

Manager
Manager
User avatar
Joined: 04 Oct 2011
Posts: 225
Location: India
Concentration: Entrepreneurship, International Business
GMAT 1: 440 Q33 V13
GMAT 2: 0 Q0 V0
GPA: 3
Followers: 0

Kudos [?]: 25 [0], given: 44

Re: A certain rabbit population quadruples every three years. [#permalink] New post 10 Jan 2013, 23:30
Marcab wrote:
Hii Shan.
If you are pretty comfortable with the logical method, then don't get confuse with this one. Anyways, here is the clarification of my method:
y(t)=y(0)*4^{t/I}

where y(t)= population after 6 years.
y(0)=current population=81
4- multiplying factor.( Since here its given that population is quadrupling, hence 4)
t-time duration given=6
I-time interval during which the population quadruples=3

The relation becomes:
y(t)=81*4^{6/3}
y(t)=81*4^2
y(t)=81*16 or 1296.

On dividing this by # of rabbits, you will get the # of wolves.

Hope that helps.



Ya thanks dude..
I got this now..

But i just wanna confirm is this standard formula for these population sums? or it depends on problem ??
_________________

GMAT - Practice, Patience, Persistence
Kudos if u like :)

Expert Post
Verbal Forum Moderator
Verbal Forum Moderator
User avatar
Status: Preparing for the another shot...!
Joined: 03 Feb 2011
Posts: 1425
Location: India
Concentration: Finance, Marketing
GPA: 3.75
Followers: 126

Kudos [?]: 571 [0], given: 62

GMAT ToolKit User GMAT Tests User Premium Member
Re: A certain rabbit population quadruples every three years. [#permalink] New post 11 Jan 2013, 03:42
Expert's post
With proper practice, this relation can be accurately used as the formula.
_________________

Prepositional Phrases Clarified|Elimination of BEING| Absolute Phrases Clarified
Rules For Posting
www.Univ-Scholarships.com

SVP
SVP
User avatar
Joined: 09 Sep 2013
Posts: 1844
Followers: 167

Kudos [?]: 33 [0], given: 0

Premium Member
Re: A certain rabbit population quadruples every three years. [#permalink] New post 28 Jan 2014, 13:17
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.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Intern
Intern
avatar
Joined: 24 Jul 2013
Posts: 2
Followers: 0

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

Re: A certain rabbit population quadruples every three years. [#permalink] New post 29 Jan 2014, 13:26
MacFauz wrote:
Marcab wrote:
MacFauz wrote:
Going to have a go at Problem Solving.. My own question, so no official answer. Please provide your feedback on how you found the question to be and anyway that I can make it clearer.. :)

A certain rabbit population quadruples every three years. The population today is 81. Exactly six years from today, the entire population will be fed to a pack of wolves. If each wolf eats exactly 12 rabbits, how many wolves can be fed using this rabbit population?

A. 54
B. 81
C. 108
D. 216
E. 324

[Reveal] Spoiler:
My Answer is C


y(t)=y(0) * 4^[t/I]
where:
y(t)=population after given number of years.
y(0)=initial population
t=time
I=amount of the time for the quantity to double.
Putting the respective values, we get population after 6 years as 1296.
Divide this by the exact capacity of wolves, and we get 108 as the answer.

Logical method:
the population is quadrupling two times. So find the population as soon as it quadruples for the first time. Then multiply the result again by 4 to get the population after 6 years.
And then the same.

+1C.

Btw Macfauz, you may apply to GMAC. I am quite certain that within a year or two, you may be writing questions for future GMAT takers.
Good Luck.


Haha.. Thanks Marcab.. Hopefully will be able to come up with more questions here before I can do that.. :)

Btw.. For the question.. We can save some time on the multiplication by keeping the final population in the form

3^4 * 2^4. Dividing this by 12 we get : \frac{3^4 * 2^4}{2^2 * 3} = 3^3 * 2^2 = 108


Good idea! I saw that all the answers had differing unit digits, so i just kept track of unit digit to arrive at the answer. The answer basically boils down 81* 4^6/12 i.e
27*4^5, and we know that unit digit of power of 4 alternates between 4 and 6 with unit digit of odd power of 4 being 4 , so the answer should end with 8!
Re: A certain rabbit population quadruples every three years.   [#permalink] 29 Jan 2014, 13:26
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic A certain population of bacteria doubles every 10 minutes. Bunuel 4 05 Jan 2014, 12:05
13 Experts publish their posts in the topic The population of locusts in a certain swarm doubles every joyseychow 11 12 Feb 2010, 22:33
Experts publish their posts in the topic A certain culture of bacteria quadruples every hour. If a beatgmat 7 13 Sep 2007, 08:24
The cottontail rabbit population in Orange County, buckkitty 7 19 Feb 2007, 14:02
A certain culture of bacteria quadruples every hour. If a Yurik79 6 17 Jan 2006, 02:48
Display posts from previous: Sort by

A certain rabbit population quadruples every three years.

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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®.