Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 24 Mar 2010
Posts: 71

In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
01 Aug 2014, 00:52
Question Stats:
58% (01:36) correct 42% (02:07) wrong based on 379 sessions
HideShow timer Statistics
In a jar there are 21 white balls, 24 green balls and 32 blue balls. How many balls must be taken out in order to make sure we have 23 balls of the same color? a) 23 b) 46 c) 57 d) 66 e) 67
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
Start to fall in love with GMAT <3




Math Expert
Joined: 02 Sep 2009
Posts: 65184

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
01 Aug 2014, 06:18




Current Student
Status: Chasing my MBB Dream!
Joined: 29 Aug 2012
Posts: 1094
Location: United States (DC)
WE: General Management (Aerospace and Defense)

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
01 Aug 2014, 01:02
LucyDang wrote: In a jar there are 21 white balls, 24 green balls and 32 blue balls. How many balls must be taken out in order to make sure we have 23 balls of the same color?
a) 23 b) 46 c) 57 d) 66 e) 67 Here, we need to find minimum number of marbles to be taken out to get 23 marbles of same color. For a instance, if we take 21 white marbles 1st and followed by 22 Green and then 22 Blue. Total will be 21 + 22+ 22= 65 draws. If we choose either Green or Blue next time. This will bring the total of either of these colored marble to 23. So Minimum we need to take 65+1 = 66 Times to get 23 marbles of same color(either Green or Blue). Answer : D. Hope it helps.
_________________




Manager
Joined: 28 Apr 2014
Posts: 182

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
06 Aug 2014, 03:07
I think the trick is in the scope shifting so 23 of one colour can be either in the jar by removing other marbles or outside the jar as a result of being moved out.



Intern
Joined: 16 Jan 2015
Posts: 1

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
16 Jan 2015, 12:52
The answer is 23.
Remember? The balls are in a jar. Jars are made of glass so you can see the colors of the ones that you wanted to take out.



Board of Directors
Joined: 17 Jul 2014
Posts: 2422
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
28 Oct 2015, 17:36
very tricky, and the wording is confusing.
23 of the same color must be left in the jar or outside? if in the jar, then we need to take at least 21 out + 1 green and 32 blue or 21 white 24 green and 9 blue. but neither works, so it must be the case that we need to take out, and see if we have at least 23 of the same kind. to make sure that we have 23 of the same kind, we need to take 21 white, 23 blue or green and 22 blue or green. this gives us a total of 66. what is the source of this question?



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 10664
Location: Pune, India

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
28 Oct 2015, 21:17
mvictor wrote: very tricky, and the wording is confusing.
23 of the same color must be left in the jar or outside? if in the jar, then we need to take at least 21 out + 1 green and 32 blue or 21 white 24 green and 9 blue. but neither works, so it must be the case that we need to take out, and see if we have at least 23 of the same kind. to make sure that we have 23 of the same kind, we need to take 21 white, 23 blue or green and 22 blue or green. this gives us a total of 66. what is the source of this question? Actually, the wording of the question is quite standard. How many do you need to take out to ensure that you have 23 of the same colour? means that out of the balls taken out, we need to ensure that there should be 23 of the same colour.
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >



SVP
Status: It's near  I can see.
Joined: 13 Apr 2013
Posts: 1676
Location: India
Concentration: International Business, Operations
GPA: 3.01
WE: Engineering (Real Estate)

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
09 Apr 2019, 10:01
VeritasKarishma wrote: mvictor wrote: very tricky, and the wording is confusing.
23 of the same color must be left in the jar or outside? if in the jar, then we need to take at least 21 out + 1 green and 32 blue or 21 white 24 green and 9 blue. but neither works, so it must be the case that we need to take out, and see if we have at least 23 of the same kind. to make sure that we have 23 of the same kind, we need to take 21 white, 23 blue or green and 22 blue or green. this gives us a total of 66. what is the source of this question? Actually, the wording of the question is quite standard. How many do you need to take out to ensure that you have 23 of the same colour? means that out of the balls taken out, we need to ensure that there should be 23 of the same colour. VeritasKarishma : Not able to understand what the question is asking and how to imagine this situation of marbles. Please help.
_________________
"Do not watch clock; Do what it does. KEEP GOING."



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 10664
Location: Pune, India

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
09 Apr 2019, 20:25
AkshdeepS wrote: VeritasKarishma wrote: mvictor wrote: very tricky, and the wording is confusing.
23 of the same color must be left in the jar or outside? if in the jar, then we need to take at least 21 out + 1 green and 32 blue or 21 white 24 green and 9 blue. but neither works, so it must be the case that we need to take out, and see if we have at least 23 of the same kind. to make sure that we have 23 of the same kind, we need to take 21 white, 23 blue or green and 22 blue or green. this gives us a total of 66. what is the source of this question? Actually, the wording of the question is quite standard. How many do you need to take out to ensure that you have 23 of the same colour? means that out of the balls taken out, we need to ensure that there should be 23 of the same colour. VeritasKarishma : Not able to understand what the question is asking and how to imagine this situation of marbles. Please help. Think about a simpler case. Say you have a box with 2 red balls, 2 blue balls and 2 white balls. Now you need to take out some balls to ensure you have two fo the same colour. How many balls do you need to take out to ENSURE that you have 2 balls of same colour. Say, you took out a red ball. Then a blue ball. Then a white ball. You still don't have 2 balls of same colour. Now the next ball you take out will make it two balls of same colour. So we need to take out 4 balls to ENSURE that there are 2 of the same colour. This is the same case here. Now, review the original question and solution.
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >



Intern
Joined: 01 Dec 2018
Posts: 42

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
30 Jul 2019, 02:07
Gnpth wrote: LucyDang wrote: In a jar there are 21 white balls, 24 green balls and 32 blue balls. How many balls must be taken out in order to make sure we have 23 balls of the same color?
a) 23 b) 46 c) 57 d) 66 e) 67 Here, we need to find minimum number of marbles to be taken out to get 23 marbles of same color. For a instance, if we take 21 white marbles 1st and followed by 22 Green and then 22 Blue. Total will be 21 + 22+ 22= 65 draws. If we choose either Green or Blue next time. This will bring the total of either of these colored marble to 23. So Minimum we need to take 65+1 = 66 Times to get 23 marbles of same color(either Green or Blue). Answer : D. Hope it helps. Hi! Can you please explain that why are we taking only 22 marbles for Green? The worst case scenario will be when last 3 are of different color and the one we pick will result in all of same color. Hence, 21+23+23  3 + 1 = 65.



Manager
Joined: 12 Apr 2018
Posts: 54

Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
Show Tags
04 Jul 2020, 03:45
kunalbean wrote: Gnpth wrote: LucyDang wrote: In a jar there are 21 white balls, 24 green balls and 32 blue balls. How many balls must be taken out in order to make sure we have 23 balls of the same color?
a) 23 b) 46 c) 57 d) 66 e) 67 Here, we need to find minimum number of marbles to be taken out to get 23 marbles of same color. For a instance, if we take 21 white marbles 1st and followed by 22 Green and then 22 Blue. Total will be 21 + 22+ 22= 65 draws. If we choose either Green or Blue next time. This will bring the total of either of these colored marble to 23. So Minimum we need to take 65+1 = 66 Times to get 23 marbles of same color(either Green or Blue). Answer : D. Hope it helps. Hi! Can you please explain that why are we taking only 22 marbles for Green? The worst case scenario will be when last 3 are of different color and the one we pick will result in all of same color. Hence, 21+23+23  3 + 1 = 65. We are taking only 22 marbles for Green because 1 more marble would suffice our need i.e. 23 marbles of same colour. So we are trying to reach a case where we are just one short of a marble such that any marble pick would help in reaching the required condition.




Re: In a jar there are 21 white balls, 24 green balls and 32
[#permalink]
04 Jul 2020, 03:45




