|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 18 Oct 2010
Posts: 82
Followers: 1
Kudos [?]:
55
[3] , given: 26
|
A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
 05 May 2012, 03:08
3
This post received
KUDOS
Question Stats:
100% (02:27) correct
0% (00:00) wrong based on 0 sessions
A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that they will both be not blue?
A. 15/28
B. 1/4
C. 9/16
D. 1/32
E. 1/16
Hi I have a confusion as to how to solve this question , if somebody can help me ?
|
|
|
|
|
|
|
GMAT Club team member
Joined: 02 Sep 2009
Posts: 11515
Followers: 1791
Kudos [?]:
9536
[3] , given: 826
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
05 May 2012, 03:26
3
This post received
KUDOS
BhaskarPaul wrote: A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that they will both be not blue?
A. 15/28
B. 1/4
C. 9/16
D. 1/32
E. 1/16
Hi I have a confusion as to how to solve this question , if somebody can help me ? The question is a bit ambiguous. I guess we are asked to find the probability that neither of the cards drawn is blue, if so then P=P(not blue)*P(not blue)=6/8*5/7=15/28. Answer: A. One can interpret the question as: what is the probability that we don't have (blue, blue) case then P=1-P(blue, blue)=1-2/8*1/7=27/28. P.S. Please post PS questions in the PS subforum: gmat-problem-solving-ps-140/ and DS questions in the DS subforum: gmat-data-sufficiency-ds-141/ No posting of PS/DS questions is allowed in the main Math forum.
_________________
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: 18 Oct 2010
Posts: 82
Followers: 1
Kudos [?]:
55
[7] , given: 26
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
05 May 2012, 04:04
7
This post received
KUDOS
Thanks Bunuel for the prompt response.
I quess the these two questions should clear the concept
1)Seven beads are in a bag: three blue, two red, and two green. If three beads are randomly drawn from the bag, what is the probability that NONE of them are blue?
answer: (4/7) x (3/6) x (2/5) = 4/35
2)Seven beads are in a bag: three blue, two red, and two green. If three beads are randomly drawn from the bag, what is the probability that they are not all blue?
A. 5/7
B. 23/24
C. 6/7
D. 34/35
E. 8/13
so should we work like this : probability of all blue 3/7*2/6*1/6=1/35
none blue : 1-(1/35)= 34/35
we should be clear of the wordings , shouldn't we ?
|
|
|
|
|
|
Intern
Joined: 05 Apr 2012
Posts: 45
Followers: 0
Kudos [?]:
8
[3] , given: 12
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
07 May 2012, 16:43
3
This post received
KUDOS
Joy111 wrote: A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that they will both be not blue?
A. 15/28
B. 1/4
C. 9/16
D. 1/32
E. 1/16
Hi I have a confusion as to how to solve this question , if somebody can help me ? hello I have computed the probability for both Cards to be blue and substract one hence total card to 8 probability for the first card 2/8 OR 1/4 For the second 1/7 HENCE 1/28 FOR CARDS 1-1/28 = 27/28 HOPE this helps best regards
|
|
|
|
|
|
Manager
Joined: 18 Oct 2010
Posts: 82
Followers: 1
Kudos [?]:
55
[0], given: 26
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
07 May 2012, 18:59
keiraria wrote: Joy111 wrote: A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that they will both be not blue?
A. 15/28
B. 1/4
C. 9/16
D. 1/32
E. 1/16
Hi I have a confusion as to how to solve this question , if somebody can help me ? hello I have computed the probability for both Cards to be blue and substract one hence total card to 8 probability for the first card 2/8 OR 1/4 For the second 1/7 HENCE 1/28 FOR CARDS 1-1/28 = 27/28 HOPE this helps best regards @keiraria Thanks for your help but can you solve this one for me too, its same as above only the language has been changed , its NONE now . If it states that both are not blue then one can be blue , try this one below. A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that NONE are blue?
|
|
|
|
|
|
Intern
Joined: 05 Apr 2012
Posts: 45
Followers: 0
Kudos [?]:
8
[2] , given: 12
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
11 May 2012, 18:41
2
This post received
KUDOS
Joy111 wrote: keiraria wrote: Joy111 wrote: A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that they will both be not blue?
A. 15/28
B. 1/4
C. 9/16
D. 1/32
E. 1/16
Hi I have a confusion as to how to solve this question , if somebody can help me ? hello I have computed the probability for both Cards to be blue and substract one hence total card to 8 probability for the first card 2/8 OR 1/4 For the second 1/7 HENCE 1/28 FOR CARDS 1-1/28 = 27/28 HOPE this helps best regards @keiraria Thanks for your help but can you solve this one for me too, its same as above only the language has been changed , its NONE now . If it states that both are not blue then one can be blue , try this one below. A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that NONE are blue? hello Joy thanks for asking me . in fact the way the question is asked has double meaning and it is a little ambigious it is noone are blue it is what I have done :27/28 but if it is that both can not be blue that is the probability to have noNE blue + the probablity to have maximum one blue and hence one of any other colors hence or case 27/28+ 2/8x6/7 Hope it is right and make sense to you best regards
|
|
|
|
|
|
Manager
Joined: 18 Oct 2010
Posts: 82
Followers: 1
Kudos [?]:
55
[1] , given: 26
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
11 May 2012, 23:53
1
This post received
KUDOS
@ keira
Thanks for your help but can you solve this one for me too, its same as above only the language has been changed , its NONE now .
If it states that both are not blue then one can be blue , try this one below.
A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that NONE are blue?[/quote]
hello Joy
thanks for asking me . in fact the way the question is asked has double meaning and it is
a little ambigious
it is noone are blue it is what I have done :27/28
but if it is that both can not be blue
that is the probability to have noNE blue + the probablity to have maximum one blue and hence one of any other colors
hence or case
27/28+ 2/8x6/7
Hope it is right and make sense to you
best regards[/quote]
I quess the these two questions should clear the concept
1)Seven beads are in a bag: three blue, two red, and two green. If three beads are randomly drawn from the bag, what is the probability that NONE of them are blue?
answer: (4/7) x (3/6) x (2/5) = 4/35
2)Seven beads are in a bag: three blue, two red, and two green. If three beads are randomly drawn from the bag, what is the probability that they are not all blue?
A. 5/7
B. 23/24
C. 6/7
D. 34/35
E. 8/13
so should we work like this : probability of all blue 3/7*2/6*1/6=1/35
none blue : 1-(1/35)= 34/35
for none you do not have to subtract from one
|
|
|
|
|
|
Intern
Joined: 28 Feb 2012
Posts: 2
Followers: 0
Kudos [?]:
0
[0], given: 3
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
20 Oct 2012, 22:01
Joy111 wrote: A certain deck of cards contains 2 blue cards, 2 red cards, 2 yellow cards, and 2 green cards. If two cards are randomly drawn from the deck, what is the probability that they will both be not blue?
A. 15/28
B. 1/4
C. 9/16
D. 1/32
E. 1/16
Hi I have a confusion as to how to solve this question , if somebody can help me ? The question asks " they will both be not blue". Considering that these are draws without replacement there are following possibilities : draw 1, draw 2 ===== ===== 1) Not Blue, Blue; 2) Blue, Not Blue; 3) Blue, Blue; 4) Not Blue, not Blue; The answer has to be either P(4) OR all exclusion of the 3 previous conditions i.e. 1- [P(1) + P(2) + P(3)] => neither of the draws are blue P(4) = 6/8*5/7=15/28 1- [P(1) + P(2) + P(3)] = 1 - [ (6/8 * 2/7) + (2/8*6/7) + (2/8*1/7)] = 1 - [26/8*7] = 1 - [13/28] = 15/28 both approaches have same answer
|
|
|
|
|
|
Manager
Joined: 15 Aug 2012
Posts: 50
Location: India
Concentration: Technology, Strategy
GPA: 3.6
WE: General Management (Computer Software)
Followers: 0
Kudos [?]:
7
[0], given: 5
|
A certain deck of cards contains 2 blue cards, 2 red cards, [#permalink]
13 Nov 2012, 19:36
Probability that both are not blue means both are other colors(except blue)
6C2 / 8C2 = 15/28
|
|
|
|
|
|
Intern
Joined: 10 Nov 2012
Posts: 13
Concentration: Finance, International Business
GMAT Date: 01-16-2013
GPA: 3.37
WE: Management Consulting (Consulting)
Followers: 0
Kudos [?]:
0
[0], given: 6
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards, [#permalink]
13 Nov 2012, 23:15
Answer = 6C2 / 8C2
=15/28
Total ways of selecting card = 8C2
Favorable = 6C2 (neglecting 2 blue cards)
PS: You did not consider the case of atleast one blue. which can be picked 12 ways.
=1-2C2/8C2-12/8C2
=1-(1/28)-(12/28)
=(28-1-12)/28
=15/28
|
|
|
|
|
|
|
Re: A certain deck of cards contains 2 blue cards, 2 red cards,
[#permalink]
13 Nov 2012, 23:15
|
|
|
|
|
|
|
|
|
Similar topics |
Author |
Replies |
Last post |
|
Similar
Topics:
|
 |
|
|
A certain deck of cards contains 2 blue cards, 2 red cards,
|
boksana |
12 |
19 Jul 2004, 12:31 |
|
|
|
|
A certain deck of cards contains 2 blue cards, 2 red cards,
|
crackgmat3 |
10 |
10 Sep 2004, 13:10 |
 |
|
|
A deck of cards contains 2 blue cards and 5 red cards. A
|
popew626 |
4 |
19 Sep 2005, 13:10 |
|
|
|
|
A certain deck of cards contains 2 blue cards, 2 red cards,
|
old_dream_1976 |
3 |
22 Feb 2006, 22:05 |
|
|
|
|
A certain deck of cards contains 2 blue cards, 2 red cards,
|
paam0101 |
12 |
23 Jan 2007, 12:42 |
|
|
|
|
|
|
close
