Consider a discrete random variable $X$ whose probabilities are given below. The standard deviation of the random variable is $\_\_\_\_\_\_\_\_\_$ (round off to one decimal place).
$$\begin{array}{|c|c|c|c|c|} \hline x_i & 1 & 2 & 4 & 8 \\ \hline P(X = x_i) & 0.3 & 0.1 & 0.3 & 0.3 \\ \hline \end{array} $$
