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

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Manager
Joined: 01 Nov 2005
Posts: 126
Followers: 1

Kudos [?]: 25 [0], given: 0

There are 8 TV sets, 6 are color and 2 are black and white. [#permalink]  04 Sep 2006, 09:47
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0% (00:00) correct 0% (00:00) wrong based on 0 sessions
There are 8 TV sets, 6 are color and 2 are black and white. If 2 sets are selected at random, what is the probability that at least one of the 2 sets is black and white.
Senior Manager
Joined: 14 Aug 2006
Posts: 365
Followers: 1

Kudos [?]: 3 [0], given: 0

the different combinations: 8c2 = 28
only color : 6c2 = 15

so atleast one b&w: 13;

another way is by finding the combinations of each b&w with the colors = 12 + both b&w = 13;
Current Student
Joined: 03 Aug 2006
Posts: 116
Followers: 4

Kudos [?]: 144 [0], given: 3

Another way of looking at it.
Probability that atleast one TV is B&W = 1 - Probability that both TV's are color.

Probability that both TV's are color = 6/8 * 5/7 = 15/28
Probability that atleast one TV is B&W = 1 - 15/28 = 13/28
CEO
Joined: 20 Nov 2005
Posts: 2913
Schools: Completed at SAID BUSINESS SCHOOL, OXFORD - Class of 2008
Followers: 18

Kudos [?]: 123 [0], given: 0

Prob of both color = 6/8 * 5/7 = 15/28

prob of atleast one BW = 1-15/28 = 13/28
_________________

SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

Last edited by ps_dahiya on 05 Sep 2006, 13:41, edited 1 time in total.
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