Author 
Message 
TAGS:

Hide Tags

Manager
Joined: 18 Oct 2010
Posts: 79

A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
Show Tags
05 May 2012, 03:08
3
This post received KUDOS
1
This post was BOOKMARKED
Question Stats:
85% (01:00) correct
15% (01:36) wrong based on 65 sessions
HideShow timer Statistics
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 ?
Official Answer and Stats are available only to registered users. Register/ Login.



Manager
Joined: 18 Oct 2010
Posts: 79

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
Show Tags
05 May 2012, 04:04
8
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 ?



Math Expert
Joined: 02 Sep 2009
Posts: 39759

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
Show Tags
05 May 2012, 03:26
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=1P(blue, blue)=12/8*1/7=27/28. P.S. Please post PS questions in the PS subforum: gmatproblemsolvingps140/ and DS questions in the DS subforum: gmatdatasufficiencyds141/ No posting of PS/DS questions is allowed in the main Math forum.
_________________
New to the Math Forum? Please read this: All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
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. ,11 Mixed Questions, 12 Fresh Meat 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., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 05 Apr 2012
Posts: 47

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
Show Tags
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 11/28 = 27/28 HOPE this helps best regards



Intern
Joined: 05 Apr 2012
Posts: 47

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
Show Tags
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 11/28 = 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: 79

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
Show Tags
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



Manager
Joined: 18 Oct 2010
Posts: 79

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
Show Tags
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 11/28 = 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: 28 Feb 2012
Posts: 2

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
Show Tags
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: 110
Location: India
Concentration: Technology, Strategy
GPA: 3.6
WE: Consulting (Computer Software)

A certain deck of cards contains 2 blue cards, 2 red cards, [#permalink]
Show Tags
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: 21
Concentration: Finance, International Business
GMAT Date: 01162013
GPA: 3.37
WE: Management Consulting (Consulting)

Re: A certain deck of cards contains 2 blue cards, 2 red cards, [#permalink]
Show Tags
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. =12C2/8C212/8C2 =1(1/28)(12/28) =(28112)/28 =15/28



Intern
Joined: 01 Jun 2013
Posts: 10

A certain deck of cards contains 2 blue [#permalink]
Show Tags
02 Nov 2015, 04:51
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 are not blue?
A. 15/28
B. 1/4
C. 9/16
D. 1/32
E. 1/16
This is a post from one of the earlier posts in the forum. All the replies assumed that the cards are drawn one by one, but this assumption is not mentioned in the question. Why cannot we draw 2 cards together and get the answer as 6/8.



Intern
Joined: 01 Nov 2015
Posts: 7

Re: A certain deck of cards contains 2 blue [#permalink]
Show Tags
02 Nov 2015, 05:03
sd.1223 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 are not blue?
A. 15/28
B. 1/4
C. 9/16
D. 1/32
E. 1/16
This is a post from one of the earlier posts in the forum. All the replies assumed that the cards are drawn one by one, but this assumption is not mentioned in the question. Why cannot we draw 2 cards together and get the answer as 6/8. Hi sd.1223, I also had the same problem However, the default assumption is that cards are always drawn one by one unless there is clear indication that they will be drawn together / drawn with replacement.




Re: A certain deck of cards contains 2 blue
[#permalink]
02 Nov 2015, 05:03








Similar topics 
Author 
Replies 
Last post 
Similar Topics:




If 2 cards are selected at random from the deck of 52 cards then What

GMATinsight 
1 
27 Jul 2015, 05:53 

7


There are 2 decks of cards. The first deck has a 100 cards labelled...

kdatt1991 
5 
23 Jul 2016, 08:43 



A deck of cards contain 2 red , 3 blue , 4 green cards. Three cards ar

rxs0005 
8 
01 Sep 2010, 23:51 

4


A deck of 9 cards contains 2 red cards, 3 blue cards, and 4 green card

gmatcracker2010 
2 
29 Mar 2016, 13:46 

8


In a stack of cards, 9 cards are blue and the rest are red

Jcpenny 
9 
30 Apr 2016, 04:35 



