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(TNX Sashing and aaron777)now try this---jim?
in a box, there are 6 red balls and 7 blue balls.Two blue balls are drawn in the first and second draw. assuming the balls are not returned, what is the probability of getting at least 2 red balls in the next three draws?
2 Answers
- sahsjingLv 71 decade agoFavorite Answer
After you draw two blue balls, the remaining balls are 6 red and 5 blue. The probability can be calculated by subtracting its supplementary probability from 1.
p = 1 - [6P0 * 5P3 + 3C1 * 6P1 * 5P2]/11P3
where P stands for permutation, 6P0 * 5P3 stands for picking none of the red balls, and 3C1 * 6P1 * 5P2 stands for picking one red ball and two blue balls. Since the red ball can be the first pick, the second pick or the third pick, you add a factor 3C1.
