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袋子里有3枚硬币:1枚总出现正面(H),2枚公平(J)。随机取一枚并掷一次:出现正面。是硬币H的概率是多少?
袋子里有3枚硬币:1枚总出现正面(H),2枚公平(J)。随机取一枚并掷一次:出现正面。是硬币H的概率是多少?
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