It is currently 18 Oct 2017, 22:54

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# There are 3 black balls and 10 white balls. If one is to pick 5 balls,

Author Message
TAGS:

### Hide Tags

Intern
Joined: 06 Nov 2011
Posts: 36

Kudos [?]: 8 [0], given: 50

Location: Germany
Concentration: Entrepreneurship, General Management
GMAT Date: 03-10-2012
GPA: 3
There are 3 black balls and 10 white balls. If one is to pick 5 balls, [#permalink]

### Show Tags

21 Nov 2011, 11:27
00:00

Difficulty:

(N/A)

Question Stats:

50% (01:45) correct 50% (02:39) wrong based on 4 sessions

### HideShow timer Statistics

I am struggling with this question to solve (Source:its from a math book)

There are 3 black balls and 10 white balls. If one is to pick 5 balls, What is the probability of picking 2 black and 3 white?

[Reveal] Spoiler:
$$\frac{C^3_2*C^{10}_3}{C^{15}_5}=28%$$

Is there another approach?

Kudos [?]: 8 [0], given: 50

Manager
Joined: 31 May 2011
Posts: 85

Kudos [?]: 65 [0], given: 4

Location: India
GMAT Date: 12-07-2011
GPA: 3.22
WE: Information Technology (Computer Software)
Re: There are 3 black balls and 10 white balls. If one is to pick 5 balls, [#permalink]

### Show Tags

21 Nov 2011, 12:14
M3tm4n wrote:
I am struggling with this question to solve (Source:its from a math book)

There are 3 black balls and 10 white balls.
if one is to pick 5 balls, What is the probability of picking 2 black and 3 white?

[Reveal] Spoiler:
$$\frac{C^3_2*C^{10}_3}{C^{15}_5}=28%$$

Is there another approach?

the denominator should be 13C5 instead of 15C5

Kudos [?]: 65 [0], given: 4

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7674

Kudos [?]: 17354 [1], given: 232

Location: Pune, India
Re: There are 3 black balls and 10 white balls. If one is to pick 5 balls, [#permalink]

### Show Tags

21 Nov 2011, 23:48
1
KUDOS
Expert's post
M3tm4n wrote:
I am struggling with this question to solve (Source:its from a math book)

There are 3 black balls and 10 white balls.
if one is to pick 5 balls, What is the probability of picking 2 black and 3 white?

[Reveal] Spoiler:
$$\frac{C^3_2*C^{10}_3}{C^{15}_5}=28%$$

Is there another approach?

Picking simultaneously is same as picking one after another.

So, let's see the probability of picking BBWWW.
(3/13)*(2/12)*(10/11)*(9/10)*(8/9)

But there are many other ways possible e.g. BWWWB, WWBBW etc
Number of all such arrangements = 5!/(2!*3!)

Required answer = (3/13)*(2/12)*(10/11)*(9/10)*(8/9)*5!/(2!*3!) = 40/143
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for \$199

Veritas Prep Reviews

Kudos [?]: 17354 [1], given: 232

Manager
Joined: 13 Jul 2011
Posts: 140

Kudos [?]: 50 [2], given: 42

Concentration: Operations, Strategy
GMAT 1: 680 Q46 V37
WE: Engineering (Telecommunications)
Re: There are 3 black balls and 10 white balls. If one is to pick 5 balls, [#permalink]

### Show Tags

22 Nov 2011, 04:13
2
KUDOS
1
This post was
BOOKMARKED
Probability of picking 5 balls from 10+3 Balls is 13C5
Probability of picking 2 Black balls from 3 is 3C2
Probability of picking 3 white balls from 10 is 10C3

So finally if one has to pick 5 balls, probability of picking 2 black and 3 white from 13 balls is:
( 3C2 * 10C3 ) / 13C5 = 40/143

Kudos [?]: 50 [2], given: 42

Manager
Joined: 29 Oct 2011
Posts: 180

Kudos [?]: 158 [0], given: 19

Concentration: General Management, Technology
Schools: Sloan '16 (D)
GMAT 1: 760 Q49 V44
GPA: 3.76
Re: There are 3 black balls and 10 white balls. If one is to pick 5 balls, [#permalink]

### Show Tags

22 Nov 2011, 07:18
(3C2*10C3)/13C5 = 40/143

Kudos [?]: 158 [0], given: 19

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16681

Kudos [?]: 273 [0], given: 0

Re: There are 3 black balls and 10 white balls. If one is to pick 5 balls, [#permalink]

### Show Tags

28 Aug 2017, 22:25
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.
_________________

Kudos [?]: 273 [0], given: 0

Re: There are 3 black balls and 10 white balls. If one is to pick 5 balls,   [#permalink] 28 Aug 2017, 22:25
Display posts from previous: Sort by