If three balls are drawn one by one without replacement from a bag containing 5 white and 4 red balls, then the probability distribution of the number of white balls drawn is
If three balls are drawn one by one without replacement from a bag containing 5 white and 4 red balls, then the probability distribution of the number of white balls drawn is
Solution
The bag contains 5 white balls and 4 red balls, for a total of 9 balls. Three balls are drawn one by one without replacement. X represents the number of white balls drawn.
The total number of ways to draw 3 balls from 9 balls:
For X = 0 (no white balls, all 3 red):
Number of ways to choose 0 white from 5:
Number of ways to choose 3 red from 4:
Favorable outcomes
For X = 1 (exactly 1 white ball):
Number of ways to choose 1 white from 5:
Number of ways to choose 2 red from 4:
Favorable outcomes
For X = 2 (exactly 2 white balls):
Number of ways to choose 2 white from 5:
Number of ways to choose 1 red from 4:
Favorable outcomes
For X = 3 (all 3 white balls):
Number of ways to choose 3 white from 5:
Number of ways to choose 0 red from 4:
Favorable outcomes
The probability distribution is:
| X | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| P(X) | 1/21 | 5/14 | 10/21 | 5/42 |
Therefore, the answer is Option 2.
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