|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 29 Mar 2012
Posts: 245
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Followers: 10
Kudos [?]:
50
[0], given: 20
|
Gambling with 4 dice, what is the probability of getting an [#permalink]
 24 May 2012, 01:31
Question Stats:
48% (02:33) correct
51% (01:14) wrong based on 2 sessions
Gambling with 4 dice, what is the probability of getting an even sum? A. 3/4 B. 1/2 C. 2/3 D. 1/4 E. 1/3
_________________
My posts: Solving Inequalities, Solving Simultaneous equations, Divisibility Rules
My story: 640 What a blunder!
My page: Ed Prep
|
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11519
Followers: 1795
Kudos [?]:
9547
[2] , given: 826
|
Re: Gambling with 4 dice, what is the probability of getting an [#permalink]
24 May 2012, 01:52
2
This post received
KUDOS
cyberjadugar wrote: Gambling with 4 dice, what is the probability of getting an even sum?
A. 3/4
B. 1/2
C. 2/3
D. 1/4
E. 1/3
Looking for a one-liner answer... Even sum can be obtained in following cases: EEEE - one case. Each E can take 3 values (2, 4, or 6), so total for this case is 3^4; OOOO - one case. Each O can take 3 values (1, 3, or 5), so total for this case is 3^4; EEOO - \frac{4!}{2!2!}=6 cases (EOEO, OOEE, ...). Each E can take 3 values (2, 4, or 6) and each O can also take 3 values (1, 3, or 5), so total for this case is 6*3^2*3^2=6*3^4; Total # of outcomes when throwing 4 dice is 6^4. P=\frac{3^4+3^4+6*3^4}{6^4}=\frac{1}{2}. Answer: B. Even without any math: the probability of getting an even sum when throwing 4 dice is the same as getting an even number on one die, so it must be 1/2. Similar problem to practice: a-box-contains-100-balls-numbered-from-1-to-100-if-three-b-109279.htmlHope it helps.
_________________
PLEASE READ AND FOLLOW: 11 Rules for Posting!!!
RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory
COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. NEW!!!
DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set. NEW!!!
What are GMAT Club Tests?
25 extra-hard Quant Tests
Find out what's new at GMAT Club - latest features and updates
|
|
|
|
|
|
Manager
Joined: 29 Mar 2012
Posts: 245
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Followers: 10
Kudos [?]:
50
[0], given: 20
|
Re: Gambling with 4 dice, what is the probability of getting an [#permalink]
24 May 2012, 02:26
Hi Bunuel, The shortcut is perfect! Are you aware of any thread where we such approaches are discussed?Similar solution can be applied to problem like no. of cases A occurs before B in a sequence, no. of cases where A & B are together In both cases half of the total no. of cases would be the answer. Since, either A comes after B or before B, either A & B are together or separated. Regards,
_________________
My posts: Solving Inequalities, Solving Simultaneous equations, Divisibility Rules
My story: 640 What a blunder!
My page: Ed Prep
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11519
Followers: 1795
Kudos [?]:
9547
[0], given: 826
|
Re: Gambling with 4 dice, what is the probability of getting an [#permalink]
24 May 2012, 02:30
|
|
|
|
|
|
Senior Manager
Joined: 09 Jun 2010
Posts: 456
Followers: 0
Kudos [?]:
14
[0], given: 39
|
Re: Gambling with 4 dice, what is the probability of getting an [#permalink]
06 Feb 2013, 04:14
very hard, I want to follow this post. this is 51/51 level , I think
|
|
|
|
|
|
Senior Manager
Joined: 09 Jun 2010
Posts: 456
Followers: 0
Kudos [?]:
14
[1] , given: 39
|
Re: Gambling with 4 dice, what is the probability of getting an [#permalink]
27 Feb 2013, 05:06
1
This post received
KUDOS
probability for EEEE to happen is
1/2*1/2*1/2*1/2=A
similarly probability for OOOO and OOEE, OEOE,...(there are 6 cases)
total 8 case
add 8 cases we have 8/A=1/2
is the result.
|
|
|
|
|
|
|
Re: Gambling with 4 dice, what is the probability of getting an
[#permalink]
27 Feb 2013, 05:06
|
|
|
|
|
|
|
|
|
|
|
close
