The Number of Customers in a Line at a Supermarket

Multiple Choice

The number of customers in a line at a supermarket express checkout counter is a random variable with the following probability distribution.

$\begin{array}{l}\begin{array} { c | c | c | c | c | c | c } \boldsymbol { x } & 0 & 1 & 2 & 3 & 4 & 5 \\\hline \boldsymbol { P } ( \boldsymbol { x } ) & 0.11 & 0.22 & 0.31 & 0.16 & 0.09 & 0.11\end{array}\\\\\text { Compute the standard deviation } \sigma _ { x } \text {. }\end{array}$

A) 2.12
B) 2.23
C) 4.48
D) 1.46