<PRE><B>Question 348451</B>
 The standard deviation of test scores on a certain achievement test is 10.5 . A random sample of scores on this test had a mean of 72.8. Based on this sample, find a 90% confidence interval for the true mean of all scores. Then complete the table below.
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x-bar = 72.8
E = (invNorm(0.95))*10.5 = 1.645*10.5 = 17.27
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Carry your intermediate computations to at least three decimal places. Round your answers to one decimal place.
The lower limit of 90% confidence interval = 72-17.27 
The upper limit of 90% confidence interval = 72+17.27
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Cheers,
Stan H.
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