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A DS question changed into PS. Please tell the approach.

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by jimmiejaz » Fri Nov 07, 2008 5:37 am
Bowls X and Y each contained exactly 2 jelly beans, each of which was either red or black. One of the jelly beans in bowl X was exchanged with one of the jelly beans in bowl Y. After the exchange, what is the probability that both of the jelly beans in bowl X are black?
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by lachlanc » Fri Nov 07, 2008 8:07 am
Is it 1/4?

P(choosing red in bowl X) = 1/2
P(choosing black in bowl Y) = 1/2

1/2*1/2 = 1/4
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by logitech » Fri Nov 07, 2008 10:10 am
lachlanc wrote:Is it 1/4?

P(choosing red in bowl X) = 1/2
P(choosing black in bowl Y) = 1/2

1/2*1/2 = 1/4
Correct.

B2R1 B1R2

R2R1 B2B1

B1R2 B2R1

B1B2 R1R2

1/4
LGTCH
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