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# There are 8 TV sets, 6 are color and 2 are black-white. If 2

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Director
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There are 8 TV sets, 6 are color and 2 are black-white. If 2 [#permalink]  21 Mar 2006, 16:04
There are 8 TV sets, 6 are color and 2 are black-white. If 2 sets are selected at random, what is the probability that at least one of them is color set?
Manager
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Re: probability [#permalink]  21 Mar 2006, 16:12
joemama142000 wrote:
There are 8 TV sets, 6 are color and 2 are black-white. If 2 sets are selected at random, what is the probability that at least one of them is color set?

1 - (2c2 / 8c2)

= 27/28
Intern
Joined: 26 Feb 2006
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Re: probability [#permalink]  21 Mar 2006, 16:13
joemama142000 wrote:
There are 8 TV sets, 6 are color and 2 are black-white. If 2 sets are selected at random, what is the probability that at least one of them is color set?

What is the prob. that no colour sets are chosen in 2 attempts?
2/8 *1/7= a (too lazy to do the math)

therefore, the prob. to chose at least 2 color sets is 1-a
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Re: probability [#permalink]  24 Mar 2006, 04:03
conocieur wrote:
joemama142000 wrote:
There are 8 TV sets, 6 are color and 2 are black-white. If 2 sets are selected at random, what is the probability that at least one of them is color set?

1 - (2c2 / 8c2)

= 27/28

i'm going a lil crazy, but what is 2c2 again?? ..

i had a totally different solution
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Director
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Re: probability [#permalink]  24 Mar 2006, 04:21
Angela780 wrote:
conocieur wrote:
joemama142000 wrote:
There are 8 TV sets, 6 are color and 2 are black-white. If 2 sets are selected at random, what is the probability that at least one of them is color set?

1 - (2c2 / 8c2)

= 27/28

i'm going a lil crazy, but what is 2c2 again?? ..

i had a totally different solution

2c2 is number of ways to select 2 black/white tv sets out of 2....
Manager
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Re: probability [#permalink]  24 Mar 2006, 04:53
SimaQ wrote:
Angela780 wrote:
conocieur wrote:
joemama142000 wrote:
There are 8 TV sets, 6 are color and 2 are black-white. If 2 sets are selected at random, what is the probability that at least one of them is color set?

1 - (2c2 / 8c2)

= 27/28

i'm going a lil crazy, but what is 2c2 again?? ..

i had a totally different solution

2c2 is number of ways to select 2 black/white tv sets out of 2....

ok Sima, please bear with me.. can you break the solution down step by step?
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Director
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OK....

First of all, to get the probability that at least one of the TV sets will be color we can use the following formula....

1-(the probability of choosing balck/white tv set both times)

To get that probability we have to calculate total favourable outcomes of choosing 2 black/white tv sets... which is 2c2 since we are calculating the number of ways to choose 2 tv sets out of 2....

... and divide it by the total number of possible outcomes... which is 8c2... since we have to choose 2 tv sets out of 8...

There may be other approaches, what approach did you use?
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P(at least 1 is color) = 1 - P(both are black-white) = 1 - (2/8)(1/7) = 27/78
Manager
Joined: 12 Feb 2006
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SimaQ wrote:
OK....

First of all, to get the probability that at least one of the TV sets will be color we can use the following formula....

1-(the probability of choosing balck/white tv set both times)

To get that probability we have to calculate total favourable outcomes of choosing 2 black/white tv sets... which is 2c2 since we are calculating the number of ways to choose 2 tv sets out of 2....

... and divide it by the total number of possible outcomes... which is 8c2... since we have to choose 2 tv sets out of 8...

There may be other approaches, what approach did you use?

6 color tv..prob that 1 will be color 6/8, 2 black and white 2/7
6/8*2/7
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