<PRE><B>Question 693105</B>
I have a standard error of mean question that I am having a hard time setting up.
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 A grain mill manufactures 100 pound bags of flour. Weights of bags are normally distributed with a mean of 100 pounds and standard deviation of 15 pounds. 
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I am trying to calculate the Probability that the weight selected falls between 94 and 106 pounds as well as... 
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Determine the z-score of 94 and or 106.
z(94) = (94-100)/15 = -6/15 = -2/5 = -0.4
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z(106) = (106-100)/15 = 6/15 = +0.4
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P(94&lt;= x &lt;=106) = P(-0.4&lt;= z &lt;=0.4) = 0.3108
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...the Probability that the sample of 36 bags which will be n=36 has a mean weight between 94 and 106 pounds.
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Note: The std for the distribution of 
sample means is 15/sqrt(36) = 15/6 = 5/2
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z(94) = (94-100)/(5/2) = -6/(5/2) = -12/5 = -2.8
z(106) = (106-100)/(5/2) = +2.8
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P(96&lt;- x-bar &lt;=106) = P(-2.8&lt;= z &lt;=2.8) = 0.9949
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Comment: You will probably need a good calculator to
continue your Statistics study.  I find the TI-84 plus
does an excellent job.
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Cheers,
Stan H.
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