d
Explanation:
⇛σ=
n
∑f(x−
x
)
2
Find f(x-x^-)²
It's
313.29+806.45+474.32+72.9+58.19+532.9+605.16+0+497.29
3360.5
Now
\begin{gathered}\\ \rm\Rrightarrow \sigma=\sqrt{\dfrac{3360.5}{50}\end{gathered}
\begin{gathered}\\ \rm\Rrightarrow \sigma=\sqrt{67.21}\end{gathered}
⇛σ=
67.21
\begin{gathered}\\ \rm\Rrightarrow \sigma=8.2\end{gathered}
⇛σ=8.2
