NEW HERE? LEARN MORE
closeclose
Last visit was: 23 Apr 2024, 22:47 It is currently 23 Apr 2024, 22:47
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

In certain pool there are 30 piranhas, which eat each other.

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92883
Own Kudos [?]: 618645 [1]
Given Kudos: 81563
Send PM
CAT Tests Forum Quiz Mode
In certain pool there are 30 piranhas, which eat each other. [#permalink] New post   09 Oct 2009, 10:07
1
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

67% (00:25) correct 33% (01:39) wrong based on 23 sessions
Hide Show timer Statistics
In certain pool there are 30 piranhas, which eat each other. Once a piranha eaten 3 others it's satisfied and stops eating, what are the maximum and minimum numbers of satisfied piranhas possible?

NOTE: When piranha A eats a piranha B which ate a number of piranhas previously, it's counted that A piranha still ate only one.
NOTE: Dead satisfied piranha still counts as satisfied.

This is my Q, so please comment about the quality and difficulty level.
User avatar
rvthryet
Intern
Intern
Joined: 02 Oct 2009
Posts: 15
Own Kudos [?]: 203 [2]
Given Kudos: 5
Send PM
Re: Piranhas in the pool [#permalink] New post   10 Oct 2009, 07:55
2
Kudos
The max satisfied nine is agreed to.
The min as per me should be zero because first can be eaten by the second and second by third and third by fourth and so on... And we'll be left with one very fat yet unsatisfied piranah.. Lemme know if it is correct though..
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92883
Own Kudos [?]: 618645 [1]
Given Kudos: 81563
Send PM
CAT Tests Forum Quiz Mode
Re: Piranhas in the pool [#permalink] New post   09 Oct 2009, 11:01
1
Kudos
Expert Reply
jax91 wrote:
Bunuel wrote:
In certain pool there are 30 piranhas, which eat each other. Once a piranha eaten 3 others it's satisfied and stops eating, what are the maximum and minimum numbers of satisfied piranhas possible?

NOTE: When piranha A eats a piranha B which ate a number of piranhas previously, it's counted that A piranha still ate only one.
NOTE: Dead satisfied piranha still counts as satisfied.

This is my Q, so please comment about the quality and difficulty level.


Max piranhas satisfied :-

for a fish to be satisfied it need to eat 3. So a max of 27 fish can be eaten. So a maximum of 9 fishes can be satisfied.

Min piranhas satisfied :-

A fish needs 3 fish to be satisfied. 1 or 2 is still unstatisfied.

let 15 fish eat the other 15.

So we get 15 fish with 1 fish eaten

Let 7 eat 7.

So we get 1 with 1 and 7 with 2 eaten. Total 8.

Let the one fish with 1 eaten eat one more.

So we get 7 fish with 2 eaten each.

Now let 3 can eat 1 each.

So we get 4 with 3 satisfied.

The last one can eat 1. Which gives us 4 satisfied.



Difficulty :- moderate :). Any prob is simpler with options. (except SC :cry: !!)

Quality :- pretty good


Thanks for response.

Good thinking but...

Anyone else wants to try...
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92883
Own Kudos [?]: 618645 [1]
Given Kudos: 81563
Send PM
CAT Tests Forum Quiz Mode
Re: Piranhas in the pool [#permalink] New post   10 Oct 2009, 08:49
1
Kudos
Expert Reply
yangsta8 wrote:
Bunuel wrote:
In certain pool there are 30 piranhas, which eat each other. Once a piranha eaten 3 others it's satisfied and stops eating, what are the maximum and minimum numbers of satisfied piranhas possible?

NOTE: When piranha A eats a piranha B which ate a number of piranhas previously, it's counted that A piranha still ate only one.
NOTE: Dead satisfied piranha still counts as satisfied.

This is my Q, so please comment about the quality and difficulty level.


In terms of quality it's pretty good, but two comments:
1) You need to define what the minimum number of satisfied piranhas means, because otherwise the answer is 0.
2) If you wish to simulate gmat conditions provide options (although that makes it easier, esp with min, max problems)

For Min:
Assuming the answer is not 0, I took the approach of 1 piranha eats the next 3. So the min would be 30/4 = 7 and 2 uneaten piranha. ANS = 7

For Max:
I took the approach that
P4 ate P1-3
P7 ate P6-P4
P10 ate P9-P7
Following this pattern I arrive at 9.
Although I suspect this might be incorrect :P


Thank you for your response. I'll try to take into account points you brought up. As for min: I thought it was obvious, when asking about min number of satisfied fishes, that min can take 0 as well.

Answer:
MIN=0 (one fish eats second, second eats third and so on, no satisfied fish at the end)
MAX=9 (7 fishes eat 3 -->7*3+7=28, 2 left eat 6(3+3) from this seven --> 2+7=9)
avatar
dk19761976
Intern
Intern
Joined: 23 Jul 2012
Posts: 2
Own Kudos [?]: 3 [1]
Given Kudos: 2
Send PM
Re: In certain pool there are 30 piranhas, which eat each other. [#permalink] New post   18 Jun 2014, 04:54
1
Kudos
Fishes are given numbers as 1 to 30


(1 2 3) (4 5 6) (7 8 9) (10 11 12) (13 14 15) (16 17 18) (19 20 21)
------- ------- ------ ---------- ---------- ---------- ---------
(22 23 24) (25 26 27) 28
-------------------- ----------------------
29 30

Here as we see, satisfied phiranas are 22, 23, 24, 25, 26, 27, 28, 29 and 30 = 9


Bunuel wrote:
In certain pool there are 30 piranhas, which eat each other. Once a piranha eaten 3 others it's satisfied and stops eating, what are the maximum and minimum numbers of satisfied piranhas possible?

NOTE: When piranha A eats a piranha B which ate a number of piranhas previously, it's counted that A piranha still ate only one.
NOTE: Dead satisfied piranha still counts as satisfied.

This is my Q, so please comment about the quality and difficulty level.
User avatar
jax91
Manager
Manager
Joined: 02 Jan 2009
Posts: 50
Own Kudos [?]: 154 [0]
Given Kudos: 6
Location: India
Concentration: General
Schools:LBS
Send PM
Re: Piranhas in the pool [#permalink] New post   09 Oct 2009, 10:54
Bunuel wrote:
In certain pool there are 30 piranhas, which eat each other. Once a piranha eaten 3 others it's satisfied and stops eating, what are the maximum and minimum numbers of satisfied piranhas possible?

NOTE: When piranha A eats a piranha B which ate a number of piranhas previously, it's counted that A piranha still ate only one.
NOTE: Dead satisfied piranha still counts as satisfied.

This is my Q, so please comment about the quality and difficulty level.


Max piranhas satisfied :-

for a fish to be satisfied it need to eat 3. So a max of 27 fish can be eaten. So a maximum of 9 fishes can be satisfied.

Min piranhas satisfied :-

A fish needs 3 fish to be satisfied. 1 or 2 is still unstatisfied.

let 15 fish eat the other 15.

So we get 15 fish with 1 fish eaten

Let 7 eat 7.

So we get 1 with 1 and 7 with 2 eaten. Total 8.

Let the one fish with 1 eaten eat one more.

So we get 7 fish with 2 eaten each.

Now let 3 can eat 1 each.

So we get 4 with 3 satisfied.

The last one can eat 1. Which gives us 4 satisfied.



Difficulty :- moderate :). Any prob is simpler with options. (except SC :cry: !!)

Quality :- pretty good
User avatar
B
yangsta8
Senior Manager
Senior Manager
Joined: 31 Aug 2009
Posts: 290
Own Kudos [?]: 1040 [0]
Given Kudos: 20
Location: Sydney, Australia
 Q49  V41
Send PM
Re: Piranhas in the pool [#permalink] New post   10 Oct 2009, 08:20
Bunuel wrote:
In certain pool there are 30 piranhas, which eat each other. Once a piranha eaten 3 others it's satisfied and stops eating, what are the maximum and minimum numbers of satisfied piranhas possible?

NOTE: When piranha A eats a piranha B which ate a number of piranhas previously, it's counted that A piranha still ate only one.
NOTE: Dead satisfied piranha still counts as satisfied.

This is my Q, so please comment about the quality and difficulty level.


In terms of quality it's pretty good, but two comments:
1) You need to define what the minimum number of satisfied piranhas means, because otherwise the answer is 0.
2) If you wish to simulate gmat conditions provide options (although that makes it easier, esp with min, max problems)

For Min:
Assuming the answer is not 0, I took the approach of 1 piranha eats the next 3. So the min would be 30/4 = 7 and 2 uneaten piranha. ANS = 7

For Max:
I took the approach that
P4 ate P1-3
P7 ate P6-P4
P10 ate P9-P7
Following this pattern I arrive at 9.
Although I suspect this might be incorrect :P
User avatar
jax91
Manager
Manager
Joined: 02 Jan 2009
Posts: 50
Own Kudos [?]: 154 [0]
Given Kudos: 6
Location: India
Concentration: General
Schools:LBS
Send PM
Re: Piranhas in the pool [#permalink] New post   10 Oct 2009, 08:25
rvthryet wrote:
The max satisfied nine is agreed to.
The min as per me should be zero because first can be eaten by the second and second by third and third by fourth and so on... And we'll be left with one very fat yet unsatisfied piranah.. Lemme know if it is correct though..


totally missed that one. Great thinkin! :-D
User avatar
GMAT TIGER
VP
VP
Joined: 29 Aug 2007
Posts: 1021
Own Kudos [?]: 1726 [0]
Given Kudos: 19
Send PM
Re: Piranhas in the pool [#permalink] New post   10 Oct 2009, 12:35
Same here.
In question like this one, min. is always 0.

Max = 9 => 4+3+3+3+3+3+3+3+3


Bunuel wrote:
yangsta8 wrote:
Bunuel wrote:
In certain pool there are 30 piranhas, which eat each other. Once a piranha eaten 3 others it's satisfied and stops eating, what are the maximum and minimum numbers of satisfied piranhas possible?

NOTE: When piranha A eats a piranha B which ate a number of piranhas previously, it's counted that A piranha still ate only one.
NOTE: Dead satisfied piranha still counts as satisfied.

This is my Q, so please comment about the quality and difficulty level.


In terms of quality it's pretty good, but two comments:
1) You need to define what the minimum number of satisfied piranhas means, because otherwise the answer is 0.
2) If you wish to simulate gmat conditions provide options (although that makes it easier, esp with min, max problems)

For Min:
Assuming the answer is not 0, I took the approach of 1 piranha eats the next 3. So the min would be 30/4 = 7 and 2 uneaten piranha. ANS = 7

For Max:
I took the approach that
P4 ate P1-3
P7 ate P6-P4
P10 ate P9-P7
Following this pattern I arrive at 9.
Although I suspect this might be incorrect :P


Thank you for your response. I'll try to take into account points you brought up. As for min: I thought it was obvious, when asking about min number of satisfied fishes, that min can take 0 as well.

Answer:
MIN=0 (one fish eats second, second eats third and so on, no satisfied fish at the end)
MAX=9 (7 fishes eat 3 -->7*3+7=28, 2 left eat 6(3+3) from this seven --> 2+7=9)
User avatar
prashantbacchewar
Manager
Manager
Joined: 20 Apr 2010
Posts: 154
Own Kudos [?]: 248 [0]
Given Kudos: 28
Concentration: Finacee, General Management
Schools:ISB, HEC, Said
 Q48  V28
Send PM
Re: Piranhas in the pool [#permalink] New post   23 Sep 2010, 05:52
Great question Bunuel.. Keep posting
User avatar
sudhanshushankerjha
Intern
Intern
Joined: 04 Sep 2010
Posts: 18
Own Kudos [?]: 5 [0]
Given Kudos: 1
Send PM
Re: Piranhas in the pool [#permalink] New post   14 Oct 2010, 10:01
Hi Bunuel,
MAX=3 (7 fishes eat 3 -->7*3+7=28, 2 left eat 6(3+3) from this seven --> 2+1=3)
am I correct?
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92883
Own Kudos [?]: 618645 [0]
Given Kudos: 81563
Send PM
CAT Tests Forum Quiz Mode
Re: Piranhas in the pool [#permalink] New post   14 Oct 2010, 10:16
Expert Reply
sudhanshushankerjha wrote:
Hi Bunuel,
MAX=3 (7 fishes eat 3 -->7*3+7=28, 2 left eat 6(3+3) from this seven --> 2+1=3)
am I correct?


\(MAX=9\): (7 fishes eat 3 -->7*3+7=28, 2 left eat 6(3+3) from this seven --> 2+7=9).
User avatar
hemanthp
Manager
Manager
Joined: 31 Jul 2010
Status:Keep fighting!
Affiliations: IIT Madras
Posts: 150
Own Kudos [?]: 1246 [0]
Given Kudos: 104
 Q49  V34 GMAT 2: 720  Q50  V37
WE 1: 2+ years - Programming
WE 2: 3+ years - Product developement,
WE 3: 2+ years - Program management
Send PM
Re: Piranhas in the pool [#permalink] New post   15 Oct 2010, 23:50
good question Bunuel. I would give this a 700+ question. Thank you.
User avatar
Sourabh2012
Intern
Intern
Joined: 04 Aug 2011
Posts: 16
Own Kudos [?]: 47 [0]
Given Kudos: 20
Location: United States
Concentration: Technology, Leadership
GMAT 1: 570 Q45 V25
GPA: 4
WE:Information Technology (Computer Software)
Send PM
Re: Piranhas in the pool [#permalink] New post   17 Jan 2012, 23:19
Bunnel,

There are 30 fishes, so 10 fishes get 3 each which makes them satified so wont 10 would be the maximum # of satified piranha ? I am confused.
User avatar
Sourabh2012
Intern
Intern
Joined: 04 Aug 2011
Posts: 16
Own Kudos [?]: 47 [0]
Given Kudos: 20
Location: United States
Concentration: Technology, Leadership
GMAT 1: 570 Q45 V25
GPA: 4
WE:Information Technology (Computer Software)
Send PM
Re: Piranhas in the pool [#permalink] New post   17 Jan 2012, 23:23
Bunnel, sorry I got it :-(
User avatar
LalaB
Current Student
Joined: 23 Oct 2010
Posts: 235
Own Kudos [?]: 1111 [1]
Given Kudos: 73
Location: Azerbaijan
Concentration: Finance
Schools: HEC '15 (A)
GMAT 1: 690 Q47 V38
Send PM
GMAT ToolKit User
Re: Piranhas in the pool [#permalink] New post   18 Jan 2012, 01:52
1
Bookmarks
hurray! i solved it and got the right answer! I hope my logic is ok
I will write it down in a lengthy way to explain what I mean-

among 5 fishes 1 can eat
among 8 fishes 2 can eat
among 11 fishes 3 can eat
among 14 fishes 4 can eat
among 17 fishes 5 can eat
among 20 fishes 6 can eat
among 23 fishes 7 can eat
among 26 fishes 8 can eat
among 29 fishes 9 can eat

so, max 9 piranhas will be happy :)
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92883
Own Kudos [?]: 618645 [0]
Given Kudos: 81563
Send PM
CAT Tests Forum Quiz Mode
Re: In certain pool there are 30 piranhas, which eat each other. [#permalink] New post   22 May 2013, 03:59
Expert Reply
Bumping for review and further discussion.
User avatar
mathewmithun
Intern
Intern
Joined: 22 Jul 2010
Posts: 16
Own Kudos [?]: 127 [0]
Given Kudos: 94
Send PM
GMAT ToolKit User
Re: Piranhas in the pool [#permalink] New post   24 Sep 2013, 22:29
Bunuel wrote:
yangsta8 wrote:
Bunuel wrote:
In certain pool there are 30 piranhas, which eat each other. Once a piranha eaten 3 others it's satisfied and stops eating, what are the maximum and minimum numbers of satisfied piranhas possible?

NOTE: When piranha A eats a piranha B which ate a number of piranhas previously, it's counted that A piranha still ate only one.
NOTE: Dead satisfied piranha still counts as satisfied.

This is my Q, so please comment about the quality and difficulty level.


In terms of quality it's pretty good, but two comments:
1) You need to define what the minimum number of satisfied piranhas means, because otherwise the answer is 0.
2) If you wish to simulate gmat conditions provide options (although that makes it easier, esp with min, max problems)

For Min:
Assuming the answer is not 0, I took the approach of 1 piranha eats the next 3. So the min would be 30/4 = 7 and 2 uneaten piranha. ANS = 7

For Max:
I took the approach that
P4 ate P1-3
P7 ate P6-P4
P10 ate P9-P7
Following this pattern I arrive at 9.
Although I suspect this might be incorrect :P


Thank you for your response. I'll try to take into account points you brought up. As for min: I thought it was obvious, when asking about min number of satisfied fishes, that min can take 0 as well.

Answer:
MIN=0 (one fish eats second, second eats third and so on, no satisfied fish at the end)
MAX=9 (7 fishes eat 3 -->7*3+7=28, 2 left eat 6(3+3) from this seven --> 2+7=9)


I fell for the trap and got min as 7, but i agree totally that there could be 0 satisfied fish, while max was 9.

Good question...
GMAT Club Bot
gmatclubot
Re: Piranhas in the pool [#permalink]
24 Sep 2013, 22:29
Moderators:
Bunuel
Math Expert
92883 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions