statistics1 ItemAnalysis

statistic for teacher KR20
http://spreadsheets.google.com/pub?key=pU2ZoVWxdOsx7Tq0k0ttqFw

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Formular

1. Mean(X)=X_bar=SX/N
   
2. var(X)=Sx²=SX²/N-(SX/N)²
   

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