<PRE><B>Question 584875</B>
a)

The margin of error is equal to the radius of the confidence interval or half the width of the confidence interval.



Margin of Error:

ME = (b-a)/2, where the confidence interval is (a,b)


ME = (0.380-0.256)/2


ME = 0.062


So the margin of error is 0.062

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b)


The sample mean is the center of the confidence interval. Note: this is assuming that this is a confidence interval for the true population mean.


Sample Mean:


xbar = (a+b)/2, for some confidence interval (a,b)


xbar = (0.256 + 0.380)/2


xbar = 0.318


So the sample mean is 0.318</PRE>