Bài tập 53 trang 93 SGK Toán 11 NC

Ta có:

\(\begin{array}{*{20}{l}}
{E\left( X \right) = 0.\frac{1}{{28}} + 1.\frac{{15}}{{16}} + 2.\frac{{27}}{{56}} + 3.\frac{3}{{14}} = 1,875}\\
\begin{array}{l}
V\left( X \right) = {\left( {0 - 1,875} \right)^2}.\frac{1}{{28}} + {\left( {1 - 1,875} \right)^2}.\frac{{15}}{{56}}\\
 + {\left( {2 - 1,875} \right)^2}.\frac{{27}}{{56}} + {\left( {3 - 1,875} \right)^2}.\frac{3}{{14}} \approx 0,609
\end{array}\\
{\sigma \left( X \right) = \sqrt {V\left( X \right)}  \approx 0,781}
\end{array}\)

-- Mod Toán 11 HỌC247