Question 1204024
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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).



<pre>
    P = {{{(C[3]^2*C[4]^2 + C[3]^3*C[4]^1)/C[7]^4}}} = {{{(3*6+1*4)/35}}} = {{{22/35}}}.    <U>ANSWER</U>
</pre>

Solved (correctly).


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To see many other similar &nbsp;(and different) &nbsp;problems solved, &nbsp;look into the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/Probability-and-statistics/Elementary-Probability-problems-related-to-Combinations.lesson>Elementary Probability problems related to combinations</A> 

in this site.


Learn the subject from there.