Question 1182137: According to the growth chart that doctors use as a reference, the heights of two-year-old boys are normally distributed with mean 34.5 inches and standard deviation 1.3 inches. If six two-year old boys are selected, what is the probability that their average height will be between 34.1 and 35.2 inches.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! this is a z-test
z=(x bar-mean)/sigma/sqrt(n)
=(34.1-34.5)/1.3/sqrt(6)
=-0.4*sqrt(6)/1.3
=-0.753
and similarly, z=0.7*sqrt(6)/1.3=1.319
the probability z is between those two values is 0.6806
or
calculator 2ndVARS2nnormal cdf(34.1,35.2,34.5,(1.3/sqrt(6)))
=0.6809 (less rounding so slightly more accurate. Find out whether the z-value is to 2,3, or more decimal places.
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