GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 20 Apr 2019, 09:57

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.

Close

Request Expert Reply

Confirm Cancel

If two balls are randomly selected from a green urn contain

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Intern
Intern
User avatar
Joined: 10 Sep 2013
Posts: 25
Location: India
Concentration: Accounting, Finance
GMAT Date: 10-25-2013
GPA: 3.66
If two balls are randomly selected from a green urn contain  [#permalink]

Show Tags

New post 19 Sep 2013, 23:08
2
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

80% (01:39) correct 20% (01:47) wrong based on 125 sessions

HideShow timer Statistics

If two balls are randomly selected from a green urn containing 5 black and 5 white balls and placed into a yellow urn initially containing 5 black and 3 white balls. What is the probability that the yellow urn will contain an equal number of black and white balls after the change?

A.2/9
B.4/9
C.5/9
D.1/3
E.1/9



Can someone please answer this question..... :roll:

_________________
Strive for Excellence....!!!!!
Veritas Prep GMAT Instructor
User avatar
D
Joined: 16 Oct 2010
Posts: 9125
Location: Pune, India
Re: If two balls are randomly selected from a green urn contain  [#permalink]

Show Tags

New post 20 Sep 2013, 00:13
1
3
KK23 wrote:
If two balls are randomly selected from a green urn containing 5 black and 5 white balls and placed into a yellow urn initially containing 5 black and 3 white balls. What is the probability that the yellow urn will contain an equal number of black and white balls after the change?

A.2/9
B.4/9
C.5/9
D.1/3
E.1/9



Can someone please answer this question..... :roll:


To have equal number of black and white balls, the yellow urn must have 5 black and 5 white balls. So the balls we select out of the green urn must be both white.
Probability (first ball is white) = 5/10
Probability(second ball is white) = 4/9
Probability (both balls are white) = (5/10)*(4/9) = 2/9
_________________
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
Intern
avatar
B
Joined: 21 Nov 2016
Posts: 41
Re: If two balls are randomly selected from a green urn contain  [#permalink]

Show Tags

New post 11 Jul 2017, 10:41
VeritasPrepKarishma wrote:
KK23 wrote:
If two balls are randomly selected from a green urn containing 5 black and 5 white balls and placed into a yellow urn initially containing 5 black and 3 white balls. What is the probability that the yellow urn will contain an equal number of black and white balls after the change?

A.2/9
B.4/9
C.5/9
D.1/3
E.1/9



Can someone please answer this question..... :roll:


To have equal number of black and white balls, the yellow urn must have 5 black and 5 white balls. So the balls we select out of the green urn must be both white.
Probability (first ball is white) = 5/10
Probability(second ball is white) = 4/9
Probability (both balls are white) = (5/10)*(4/9) = 2/9


The other way around, total possibilities would be 10C2 = 45 and the selection that 2 white balls are selected out of 5 white balls would be 5C2 = 10.
So probability = 10/45 = 2/9

Please let me know if this approach is correct
GMAT Tutor
avatar
S
Joined: 24 Jun 2008
Posts: 1418
Re: If two balls are randomly selected from a green urn contain  [#permalink]

Show Tags

New post 11 Jul 2017, 10:46
Your approach is correct, yes - I prefer to solve these problems the way Karishma did above, but I think the method people will find easiest depends on how they've studied probability.
_________________
GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com
GMAT Club Bot
Re: If two balls are randomly selected from a green urn contain   [#permalink] 11 Jul 2017, 10:46
Display posts from previous: Sort by

If two balls are randomly selected from a green urn contain

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.