There are 5 red and 4 black balls in a box. If you pick out 2 balls without replacement, what is the

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There are 5 red and 4 black balls in a box. If you pick out 2 balls without replacement, what is the probability of getiing at least one red ball?


First list out our sample space. At least one means 1 or 2 red balls, so we have 3 possible draws:

1. Red, Black
2. Black, Red
3. Red, Red

List out the probabilities:

1. Red (5/9) * Black (4/8) = 5/18
2. Black (4/9) * Red (5/8) = 5/18
3. Red (5/9) * Red (4/8) = 5/18

Add these up:
3(5)/18 = 5/6