<PRE><B>Question 662340</B>
An urn contains 12 numbered balls 5 red and 7 white. A sample of 4 balls is selected.Hiw many samples have
A. Exactly 3 red balls?
B. At least 2 white balls?
C. At most one white ball? 
A. C(5,3) * C(7,1) = 10*7 = 70
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B. C(5,3)* C(7,1) + C(7,0) * C(5,4)= 10*7 + 1*5 = 75
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Cheers,
Stan H. 
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