# recitation8 - Review and Examples When you know the...

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Review and Examples When you know the population standard deviation σ , you can use this conﬁdence interval for the population mean μ : ¯ x ± z α/ 2 σ n When you do not know the population standard deviation σ , you ﬁrst estimate s (the sample standard deviation), and then compute the con- ﬁdence interval for μ using ¯ x ± t α/ 2 s n Example (Creating Conﬁdence intervals for a population mean in Excel) : The ﬁle Alcohol.xls contains the annual consumption in liters for a random sample of 50 European women. Use Excel to compute the sample mean. (Use =AVERAGE(A2:A51) ) Use Excel to compute the standard deviation (Use =STDEV(A2:A51) ) To compute the conﬁdence interval (note that we do not know σ , but we do know s ): 1. Click on “Data” -→ “Data Analysis”. 2. Select Descriptive Statistics.

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## This note was uploaded on 01/24/2011 for the course STATISTICS 19897 taught by Professor Jager,abigaill during the Fall '10 term at Kansas State University.

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recitation8 - Review and Examples When you know the...

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