Question 962269: The diameter of a brand of Ping Pong balls is approximately normally distributed, with a mean of 1.31 inches and a standard deviation of 0.08 inches. A random sample of 4 balls is selected.
-The probability is 50% that the sample mean will be between what two values, symmetrically distributed around the population mean?
Lower bound: __ inches
Upper bound: __ inches
I'm pretty sure I need to start by finding a Z score, but am having a hard time figuring which formulas I need to use, for that and to finish the problem. Thanks.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The diameter of a brand of Ping Pong balls is approximately normally distributed, with a mean of 1.31 inches and a standard deviation of 0.08 inches. A random sample of 4 balls is selected.
-The probability is 50% that the sample mean will be between what two values, symmetrically distributed around the population mean?
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Looks like you want a 50% confidence interval.
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sample mean = x-bar = 1.31
Margin of Error = ME = z*s/sqrt(n))= 0.6745*0.08/sqrt(4) = 0.0270
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50%CI:: 1.31-0.0270 < u < 1.31+0.0270
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Cheers,
Stan H.
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Lower bound: 1.2831 inches
Upper bound: 1.3369 inches
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