The standard deviation is:Find the standard deviation for the number of sleepwalkers in groups of five.

SOLUTION
We want to find the standard deviation of the data in the picture
So we need to make a table
The formula is given as
[tex]\sqrt[]{\sum^{}_{}(x-\operatorname{mean})^2.P(x)}[/tex]So we need to make a table for
[tex]\begin{gathered} x-\operatorname{mean} \\ \text{This is given as } \\ (x-x(Px) \end{gathered}[/tex]Then we square it and multiply for by P(x)
This means we need a table for
[tex](x-\operatorname{mean})^2.P(x)[/tex]Then we sum and get the square root.
The table is shown below
So the last column is
[tex]\begin{gathered} (x-xP(x))^2.P(x) \\ It\text{ is the same as } \\ (x-\operatorname{mean})^2.P(x) \end{gathered}[/tex]So let us sum
[tex]\begin{gathered} (x-xP(x))^2.P(x) \\ We\text{ will add the numbers under it. This is } \\ =2.113819605 \end{gathered}[/tex]The standard deviation becomes
[tex]\begin{gathered} S\mathrm{}D=\sqrt[]{2.113819605} \\ S\mathrm{}D=1.453898 \end{gathered}[/tex]Hence the answer is 1.45 to 2 decimal places