Answer:
32.2
Step-by-step explanation:
The given data set is:
56,78,123,34,67,91,20
The mean of this data set is
[tex]\frac{56+78+123+34+67+91+20}{7} =\frac{469}{7} =67[/tex]
The standard deviation is given by;
[tex]SD=\sqrt{\frac{\sum(x-\bar X)^2}{n} }[/tex]
[tex]SD=\sqrt{\frac{(56-67)^2+(78-67)^2+(123-67)^2+(34-67)^2+(67-67)^2+(91-67)^2+(20-67)^2}{7} }[/tex]
[tex]SD=\sqrt{\frac{7252}{7} }[/tex]
[tex]SD=\sqrt{1036}=32.2[/tex]
