統計學題目 求機率<xml><o></o>
Bag I contains 15 WHITE balls and 17 BLACK balls. Bag II contains 14 WHITE and 12 BLACK balls. One of the bag is selected by the toss of a fair coin and then 2 balls are drawn without replacing from the bag selected. If both balls drawn are WHITE, what is the probability that the bag I is selected?
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袋子1裡面有15顆白球和17顆黑球
袋子2裡面有14顆白球和12顆黑球
用一枚 硬幣的正反面來選擇袋子1或袋子2
然後我現在連續拿出2顆白球
請問我選擇袋子1的機率是多少? -*-*-
公式:P = |E|/|S|
P(B|A) = (B∩A)/P(A)
nPr= n!/(n-r)!
nCr=n!/r!(n-r)