Oct 14 08:00 PM PDT  11:00 PM PDT Join a 4day FREE online boot camp to kick off your GMAT preparation and get you into your dream bschool in R2.**Limited for the first 99 registrants. Register today! Oct 15 12:00 PM PDT  01:00 PM PDT Join this live GMAT class with GMAT Ninja to learn to conquer your fears of long, kooky GMAT questions. Oct 16 08:00 PM PDT  09:00 PM PDT EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth $100 with the 3 Month Pack ($299) Oct 19 07:00 AM PDT  09:00 AM PDT Does GMAT RC seem like an uphill battle? eGMAT is conducting a free webinar to help you learn reading strategies that can enable you to solve 700+ level RC questions with at least 90% accuracy in less than 10 days. Sat., Oct 19th at 7 am PDT Oct 20 07:00 AM PDT  09:00 AM PDT Get personalized insights on how to achieve your Target Quant Score.
Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 22 Mar 2009
Posts: 58
Schools: Darden:Tepper:UCUIC:Kenan Flager:Nanyang:NUS:ISB:UCI Merage:Emory
WE 1: 3

In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
02 Nov 2009, 11:59
Question Stats:
54% (01:24) correct 46% (01:43) wrong based on 219 sessions
HideShow timer Statistics
In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20 green balls. How many balls must be taken out in order to make sure we took out 8 of the same color? a) 8 b) 23 c) 29 d) 32 e) 53
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
Second cut is the deepest cut!!!:P



Intern
Joined: 06 Oct 2009
Posts: 6

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
02 Nov 2009, 12:23
The question asks about how many balls MUST be taken out in order to make sure we took out 8 of the same color.
Now, in this case we have to be sure about our answer when we can say we have taken out 8 balls of same color.
Favorable case will be if we take out first eight balls and all of them are of the same color. But that is a favorable case and may not always be true.
A worst case will be when you are 100% sure that you have achieved the desired result.
As in this case: if you draw out first 28 balls and they are 7 of each color, W, R, B, G. Now you know that any ball you take out next will be of any one of the above colors and hence you'll have 8 ball of same color.
So ans is 29.
I hope it's clear.



SVP
Joined: 29 Aug 2007
Posts: 1981

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
02 Nov 2009, 23:35
kylexy wrote: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20 green balls. How many balls must be taken out in order to make sure we took out 8 of the same color?
a) 8 b) 23 c) 29 d) 32 e) 53 Thats 29 in C. I love these types of questions..
_________________
Verbal: http://gmatclub.com/forum/newtotheverbalforumpleasereadthisfirst77546.html Math: http://gmatclub.com/forum/newtothemathforumpleasereadthisfirst77764.html Gmat: http://gmatclub.com/forum/everythingyouneedtoprepareforthegmatrevised77983.html
GT



Intern
Joined: 29 Jul 2009
Posts: 14
Schools: Stanford, HBS, INSEAD

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
03 Nov 2009, 16:44
I don't get why there will be 7 of each when we draw out 28 balls. Could you please elaborate?



Manager
Joined: 12 Oct 2009
Posts: 126
Schools: Columbia, INSEAD, RSM, LBS

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
04 Nov 2009, 06:08
Arora2m this one is for you :
Black Blue Yellow Green 1 1 1 1 1 1 1 1 . . . . .
similar pattern 7 times. the next ball will have to be from either of the colors and making the total tally of that color to 8 balls



Intern
Joined: 25 Oct 2009
Posts: 11

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
05 Nov 2009, 09:39
HI where do we come across these type of questions in og 11.If you could point out the question numbers it will be really greatful asap.



Director
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 860

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
12 May 2011, 04:12
nice question.
take 7 out of each color.7*4 + 1 = 29



Math Expert
Joined: 02 Sep 2009
Posts: 58320

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
12 May 2016, 15:02
kylexy wrote: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20 green balls. How many balls must be taken out in order to make sure we took out 8 of the same color?
a) 8 b) 23 c) 29 d) 32 e) 53 Check other Worst Case Scenario Questions from our Special Questions Directory to understand the concept better.
_________________



Manager
Status: IF YOU CAN DREAM IT, YOU CAN DO IT
Joined: 03 Jul 2017
Posts: 187
Location: India
Concentration: Finance, International Business

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
09 Jul 2017, 22:25
Can someone please elaborate the concept in this question. Why do we have to consider each ball of different color??



Director
Affiliations: IIT Dhanbad
Joined: 13 Mar 2017
Posts: 728
Location: India
Concentration: General Management, Entrepreneurship
GPA: 3.8
WE: Engineering (Energy and Utilities)

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
09 Jul 2017, 23:00
kylexy wrote: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20 green balls. How many balls must be taken out in order to make sure we took out 8 of the same color?
a) 8 b) 23 c) 29 d) 32 e) 53 This is a very simple question. Jar contains 15 WB, 25 RB, 10 BB, 20 GB. Now to ensure that there must be 8 balls of same colour, the best case will be, we take out 8 ball of same colour & the worst case will be when we take out 7 balls of each colours and then we take out any ball. The last ball's colour will be the colour of the 8 balls with same colour and other 7 balls will be of their respective colour. So to ensure that we have 8 balls of same colour we need to take out 7+7+7 +8 = 29 balls. Answer C.
_________________
CAT 2017 (98.95) & 2018 (98.91) : 99th percentiler UPSC Aspirants : Get my app UPSC Important News Reader from Play store. MBA Social Network : WebMaggu
Appreciate by Clicking +1 Kudos ( Lets be more generous friends.) What I believe is : "Nothing is Impossible, Even Impossible says I'm Possible" : "Stay Hungry, Stay Foolish".



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8043
Location: United States (CA)

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
12 Jul 2017, 17:05
kylexy wrote: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20 green balls. How many balls must be taken out in order to make sure we took out 8 of the same color?
a) 8 b) 23 c) 29 d) 32 e) 53 The worst case scenario would be having to draw 7 balls of each color so that we wouldn’t have 8 balls of any one color. However, if we were to remove just one more ball, regardless of the color, we would then have 8 balls of one color. Thus, we need to remove 7 x 4 + 1 = 29 balls. Answer: C
_________________
5star rated online GMAT quant self study course See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews If you find one of my posts helpful, please take a moment to click on the "Kudos" button.



Director
Joined: 19 Oct 2013
Posts: 520
Location: Kuwait
GPA: 3.2
WE: Engineering (Real Estate)

Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
Show Tags
30 Oct 2018, 14:20
kylexy wrote: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20 green balls. How many balls must be taken out in order to make sure we took out 8 of the same color?
a) 8 b) 23 c) 29 d) 32 e) 53 The maximum we can take out before we have 8 of the same color is 7 of each color. 7 * 4 = 28 Then any additional ball we take will complete a set of 8. So 29 Answer choice C Posted from my mobile device




Re: In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20
[#permalink]
30 Oct 2018, 14:20






