Question 1180447
3.1  (4/10)*(3/9)
3.2  (6/10)*(5/9)
3.3  (4/10)*(6/9)
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NOTE that in 3.3, the order matters.   If we didn't care about order and just wanted P(you end up with one white and one black) = (6/10)*(4/9) + (4/10)*(6/9), which happens to be twice that found in 3.3, and is also equal to 1 - ((3.1) +(3.2)) which should make sense intuitively (you select two balls, they are either both black, both white, or one of each color).