The weights of students in a certain school are normally distributed with a mean weight of 66 kg. 10% have a weight greater than 70kg. What percentage of students weighs between 62kg and 66kg?
The normal distribution is symmetric:
"P(W\\le66)=P(W\\ge66)=50\\%\\\\\nP(66-4=62\\le W\\le66)=\\\\\n=P(66\\le W\\le70=66+4)=\\\\\n=50\\%-P(70\\le W)=40\\%"
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