2个英语问题,翻译并解答

1.If a die is thrown 3 times, what is the probability that all throws show 6?
2.If a coin is tossed 100 times, find the theoretical standard deviation.

1.If a die is thrown 3 times, what is the probability that all throws show 6?
一个骰子掷了3次,每次都是6的几率多大?
答:1/6的3次方,即1/216
First the 216th.
2.If a coin is tossed 100 times, find the theoretical standard deviation.
一个硬币扔100次,理论上的标准差是?
sorry,忘了怎么算了……
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第1个回答  2009-07-23
标准差嘛:
就是方差的算数平方根,
方差:每一个数减去所有数的平均数再平方,
…………如此多的平方相加
再除以有多少个数,
就是方差辣,
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