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White & black rats in 3 cages

zilonis

New member
Joined
Feb 13, 2011
Messages
2
A cage contains six rats, 2 of them white and 4 of them black; a 2nd cage contains 4 rats, 2 white and 2 black; and a 3rd cage contains 5 rats, 3 white and 2 black. If one rat is selected randomly from each cage,

What is the probability that all 3 rats selected will be white?
This one I could answer: 2/6 * 2/4 * 3/5 = 1/10

What is the probability that exactly 2 of the 3 will be white?
??

What is the probability of selecting at least 2 white rats?
??

Thank you!
 

pka

Elite Member
Joined
Jan 29, 2005
Messages
7,688
zilonis said:
A cage contains six rats, 2 of them white and 4 of them black; a 2nd cage contains 4 rats, 2 white and 2 black; and a 3rd cage contains 5 rats, 3 white and 2 black. If one rat is selected randomly from each cage,
What is the probability that exactly 2 of the 3 will be white?
Calculate three probabilities and add them up.
\(\displaystyle P(W_1W_2B_3)+P(W_1B_2W_3)+P(B_1W_2W_3)\)
 
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