SOLUTION: Unsolved 2014-05-23 14:28:27 Determine a 90% confidence interval for μ if σ=5, x̄ (x bar) = 70 and n=82. Give answer interval rounded to two decimal places. Thank yo

Algebra ->  Probability-and-statistics -> SOLUTION: Unsolved 2014-05-23 14:28:27 Determine a 90% confidence interval for μ if σ=5, x̄ (x bar) = 70 and n=82. Give answer interval rounded to two decimal places. Thank yo      Log On


   

Question 877478: Unsolved 2014-05-23 14:28:27 Determine a 90% confidence interval for μ if σ=5, x̄ (x bar) = 70 and n=82. Give answer interval rounded to two decimal places. Thank you!
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Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
The critical value for a 90% confidence interval is z = 1.645 (you use a calculator or table to find this)

Given

xbar = 70
z = 1.645 (see above)
sigma = 5
n = 82
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Lower Bound

L = xbar - z*sigma/sqrt(n)
L = 70 - 1.645*5/sqrt(82)
L = 69.0917006980343
L = 69.09
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Upper Bound

U = xbar + z*sigma/sqrt(n)
U = 70 + 1.645*5/sqrt(82)
U = 70.9082993019657
U = 70.91

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The confidence interval (L,U) is (69.09, 70.91)