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勿忘初心asdf

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[交流] 求解答。菜鸟一枚。

The diameter of a population of ball bearing is normally distrubuted with a mean of 75 and a standard deviation of 8.What is the probability of the average diameter of 10 randomly selected ball bearing being greater than 77?
A、0.3751
B、0.4013
C、0.2146
D、0.021

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