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A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
05 May 2012, 02:08

3

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Difficulty:

15% (low)

Question Stats:

93% (01:47) correct
7% (00:39) wrong based on 28 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 ?

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
05 May 2012, 03:04

8

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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 NONEof 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 ?

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
05 May 2012, 02:26

3

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Expert's post

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.

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
07 May 2012, 15:43

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

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
11 May 2012, 17:41

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

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
11 May 2012, 22:53

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

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
07 May 2012, 17:59

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?

Re: A certain deck of cards contains 2 blue cards, 2 red cards [#permalink]
20 Oct 2012, 21:01

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