<PRE><B>Question 250037</B>
A sample of size n = 20 is selected from a normal population to construct a 98% confidence interval estimate for a population mean. The interval was computed to be (8.90 to 12.90). Determine the sample standard deviation. 
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xbar-E = 8.9
xbar+E = 12.9
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2xbar = 21.8
xbar = 10.9
E = 10.9-8.9 = 2
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E = s/sqrt(n)
2 = s/sqrt(20)
s = 2*sqrt(20)
s = 4sqrt(5)
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Cheers,
Stan H.</PRE>