SOLUTION: A population of women’s weights is approximately normally distributed with a mean of 140 lb and a standard deviation of 20 lb. What percentage of women weigh between 120 and 1

Question 1161349: A population of women’s weights is approximately normally distributed with a mean of 140 lb and a standard deviation of 20 lb.
What percentage of women weigh between 120 and 160 lb?
If samples of size 16 are drawn from the population of women’s weights, What is the probability that a sample mean from a sample size 16 lies above 145 lb?

Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
z=(x-mean)/sd
this is between -1 and 1 for z which is 68% by the empirical rule and 68.27% actually.
sample of size 16 means the std error of the mean is 20/sqrt(16)=5
Do the same problem with sd 5 now
z>(145-140)/5 or z>1 with probability's being 0.1587
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