SOLUTION: The lengths of pregnancies are normally distributed with a mean of 264 days and a standard deviation of 21 days. If 100 women are randomly selected, find the probability that they

Question 1161656: The lengths of pregnancies are normally distributed with a mean of 264 days and a standard deviation of 21 days. If 100 women are randomly selected, find the probability that they have a mean pregnancy between 263 days and 265 days.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
Since it is symmetric, can get 1 probability and double it.
z=(x-mean)/sd/sqrt(n)
=-1*10/21, inverting the denominator and multiplying.
=-10/21 or 0.476
want the probability of z between -.476 and +.476 which is 0.3659
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