ABCDEFGHIJKLMNOPQRSTUVWXYZ
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Given Data
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n36
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mean68
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sigma/std dev3
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Alpha0.1
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Find the critical value
-1.644853625
<- Excel defaults to the left side of the distribution, always take the absolute value of this
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Abs value of above, round to 3 decimals
1.645
<- You aren't required to used this function, just remember that this number needs to be positive
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Now calculate the EBM
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EBM0.8225
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Now you can finish the pieces for the confidence interval
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High68.8225
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Low67.1775
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The confidence interval is (67.1775, 68.8225)
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