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

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jimmiejaz: Master | Next Rank: 500 Posts; Posts: 207; Joined: Sun Mar 11, 2007 6:16 pm; Location: Mumbai; Thanked: 11 times

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

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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Source: Beat The GMAT — Problem Solving | Fri Nov 07, 2008 5:37 am

lachlanc: Senior | Next Rank: 100 Posts; Posts: 46; Joined: Mon Jul 07, 2008 12:10 pm; Location: Atlanta; Thanked: 5 times; Followed by:1 members

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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