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)
