Math
posted by Chris .
A bag contains 9 red marbles, 8 white marbles, and 6 blue marbles. You draw 4 marbles out at random, without replacement. What is the probability that all the marbles are red?
What is the probability that exactly two of the marbles are red?
The probability that exactly two of the marbles are red is...?

Math 
something
9/23 bc there are 9 red marbles and 23 marbles altogether

Math 
potato
^thats only for choosing one marble out of the bag
you have to solve for choosing 4 marbles out of the bag, and 2 of them are red 
correction  Math 
Reiny
prob(4reds)
= (9/23)(8/22)(7/21)(6/20)
= 18/1265
or
prob(4reds)
= C(9,4) / C(23,4) = 126/8855 = 18/1265
= appr .014
prob(2 out of 4 are red)
= C(9,2) * C(14,2)/C(23,4)
= 36*91/8855
= 468/1265 = appr .37
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