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Probability

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Probability [#permalink]

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New post 23 Aug 2017, 09:30
Two cards are drawn at random from pack of 52 cards , what's the probability that either both are black or both are queens?


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New post 23 Aug 2017, 09:48
We have n(s) = 52C2= 1326.
Let A = event of getting both black cards
B = event of getting both queens
A∩B = event of getting queen of black cards
n(A) = 26C2 = 325, n(B)= 4C2 = 6 and n(A∩B) = 2C2 = 1
P(A) = n(A)/n(S) = 325/1326;
P(B) = n(B)/n(S) = 6/1326 and
P(A∩B) = n(A∩B)/n(S) = 1/1326
P(A∪B) = P(A) + P(B) - P(A∩B) = 55/221

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Probability [#permalink]

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New post 23 Aug 2017, 09:49
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Drawing simultaneously or one after another without replacement?

If drawing simultaneously it is 55/221 .
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Re: Probability [#permalink]

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New post 23 Aug 2017, 10:29
sachchidanand wrote:
Two cards are drawn at random from pack of 52 cards , what's the probability that either both are black or both are queens?


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Kindly follow the rules before posting.

This question has already been discussed here : https://gmatclub.com/forum/2-cards-are- ... 06543.html
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Re: Probability   [#permalink] 23 Aug 2017, 10:29
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