SOLUTION: An urn has 7 balls that are identical except that 3 are white and 4 are red. A sample of 4 is selected randomly without replacement. What is the probability that exactly 2 are whi

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Question 1204024: An urn has 7 balls that are identical except that 3 are white and 4 are red. A sample of 4 is selected randomly without replacement.
What is the probability that exactly 2 are white and 2 are red?

What is the probability that at least 2 of the balls are white?

Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

7 balls that are identical except that 3 are white and 4 are red

What is the probability that exactly 2 are white and 2 are red?
%28C%283%2C2%29%2AC%284%2C2%29%29%2FC%287%2C4%29=18%2F35

What is the probability that at least 2 of the balls are white?

%28C%283%2C2%29%2AC%283%2C3%29%29%2FC%287%2C3%29=3%2F35

Answer by ikleyn(52775) About Me  (Show Source):
You can put this solution on YOUR website!
.
An urn has 7 balls that are identical except that 3 are white and 4 are red.
A sample of 4 is selected randomly without replacement.
(a) What is the probability that exactly 2 are white and 2 are red?
(b) What is the probability that at least 2 of the balls are white?
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        In the post by  @MathLover1,  her solution and the answer for part  (b)  both are  INCORRECT.
        I came to bring a correct solution for part  (b).


    P = %28C%5B3%5D%5E2%2AC%5B4%5D%5E2+%2B+C%5B3%5D%5E3%2AC%5B4%5D%5E1%29%2FC%5B7%5D%5E4 = %283%2A6%2B1%2A4%29%2F35 = 22%2F35.    ANSWER

Solved (correctly).

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To see many other similar  (and different)  problems solved,  look into the lesson
    - Elementary Probability problems related to combinations
in this site.

Learn the subject from there.