Bird Question: selecting finches from covered cage

zebrafinch

New member
Joined
May 30, 2008
Messages
4
A covered cage contains 12 zebra finches, 8 society finches, and 6 owl finches. If two finches are randomly selected at the same time, what is the probability that they match?

I assume that it depends on which kind of bird is pulled out first?

I think the probability of pulling out the first finch would be----Zebra (12/26) Society (8/26) Owl(6/26)

If you pull out say a Zebra on the first grab, then the second would be (12/26)(11/25)2 ?????????????

Im not sure if I am doing this right?
 

galactus

Super Moderator
Staff member
Joined
Sep 28, 2005
Messages
7,216
You're thinking on the right lines.

\(\displaystyle (12/26)(11/25)+(8/26)(7/25)+(6/26)(5/25)\)

or

\(\displaystyle \frac{C(12,2)+C(8,2)+C(6,2)}{C(26,2)}\)
 

Denis

Senior Member
Joined
Feb 17, 2004
Messages
1,492
That problem is for the birds :roll:
 
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