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标题: [求助]请教OG-196 [打印本页]

作者: saibei008 时间: 2005-8-16 06:42 标题: [求助]请教OG-196

[求助]请教OG-196(math: problem solving)

请教OG-196

The probability is 1/2 that a certain coin will turn up heads on any given toss. If the coin is to be tossed three times, what is the probability that on at least one of the tosses the coin will turn up tails? (7/8)

作者: mjiirggh 时间: 2005-8-16 13:34

总概率是1，三次全是heads的概率是1/2*1/2*1/2=1/8，用总概率减去三次全是heads的概率则等于至少有一次是tails的概率，即为1-1/8=7/8

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