[tex]x_1=-9\\x_2=3\\x_3=9\\x_4=2\\\\\overline x=\dfrac{-9+3+9+2}{4}=\dfrac54=1,25[/tex]
Odchylenie standardowe dla zestawu czterech danych to:
[tex]\sigma=\sqrt{\dfrac{(x_1-\overline x)^2+(x_2-\overline x)^2+(x_3-\overline x)^2+(x_4-\overline x)^2}4}[/tex]
Zatem:
[tex]\sigma=\sqrt{\dfrac{(-9-1{,}25)^2+(3-1{,}25)^2+(9-1{,}25)^2+(2-1{,}25)^2}4}=\\\\\\ =\dfrac{\sqrt{(-10{,}25)^2+(1{,}75)^2+(7{,}75)^2+(0{,}75)^2}}2=[/tex]
[tex]= \dfrac{\sqrt{105{,}0625+3{,}0625+60{,}0625+0{,}5625}}2= \dfrac{\sqrt{168{,}75}}2\approx6,5[/tex]
