Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 17 Sep 2014, 22:10

### 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

# In a department store prize box, 40% of the notes give...

Author Message
TAGS:
SVP
Joined: 06 Sep 2013
Posts: 1664
Location: United States
Concentration: Finance
GMAT 1: 710 Q48 V39
WE: Corporate Finance (Investment Banking)
Followers: 12

Kudos [?]: 164 [0], given: 268

In a department store prize box, 40% of the notes give... [#permalink]  18 Sep 2013, 11:31
00:00

Difficulty:

55% (hard)

Question Stats:

62% (02:57) correct 38% (02:07) wrong based on 29 sessions
In a department store prize box, 40% of the notes give the winner a dreamy vacation; the other notes are blank. What is the approximate probability that 3 out of 5 people that draw the notes one after the other, and immediately return their note into the box get a dreamy vacation?

a) 0.12
b) 0.23
c) 0.35
d) 0.45
e) 0.65
[Reveal] Spoiler: OA
Math Expert
Joined: 02 Sep 2009
Posts: 29671
Followers: 3495

Kudos [?]: 26304 [0], given: 2708

Re: In a department store prize box, 40% of the notes give... [#permalink]  18 Sep 2013, 11:39
Expert's post
jlgdr wrote:
In a department store prize box, 40% of the notes give the winner a dreamy vacation; the other notes are blank. What is the approximate probability that 3 out of 5 people that draw the notes one after the other, and immediately return their note into the box get a dreamy vacation?

a) 0.12
b) 0.23
c) 0.35
d) 0.45
e) 0.65

The probability of winning is 40% = 40/100 = 2/5.
The probability of NOT winning is 60% = 3/5.

P(WWWNN)=\frac{5!}{3!2!}*(\frac{2}{5})^3*(\frac{3}{5})^2=\frac{144}{625}\approx{23} (we multiply by \frac{5!}{3!2!}, because WWWNN scenario can occur in several ways: WWWNN, WWNWN, WNWWN, NWWWN, ... the # of such cases basically equals to the # of permutations of 5 letters WWWNN, which is \frac{5!}{3!2!}).

_________________
Re: In a department store prize box, 40% of the notes give...   [#permalink] 18 Sep 2013, 11:39
Similar topics Replies Last post
Similar
Topics:
We're giving out cash prizes to MBA CHALLENGE winners 2 05 Jan 2011, 16:57
The contest judges were told to give the prize to whomever 6 19 Nov 2007, 02:16
The first prize money of the race is $125, the second$40 3 28 May 2006, 17:17
In a department store there are 30 cubbies of different 5 22 May 2006, 06:13
DS: Department Stores 4 19 Nov 2005, 23:10
Display posts from previous: Sort by