Let x_i(1 ≤ i ≤ 10) be ten observations of a random variable X. If Σ_i=1^10(x_i- p )=3 and Σ_i=1^10(x_i- p )^2=9 where 0 ≠ p ∈ R, then the standard…

Let $\displaystyle x_i(1 \leq i \leq 10)$ be ten observations of a random variable X. If $\displaystyle \sum_{i=1}^{10}\left(x_i-\mathrm{p}\right)=3$ and $\displaystyle \sum_{i=1}^{10}\left(x_i-\mathrm{p}\right)^2=9$ where $\displaystyle 0 \neq \mathrm{p} \in \mathbf{R}$, then the standard deviation of these observations is :