Đáp án:
\(\overline {{M_X}} = 13\)
Giải thích các bước giải:
\(\begin{array}{l}
2{p_{{X_1}}} + {n_{{X_1}}} = 18 \Rightarrow {n_{{X_1}}} = 18 - 2{p_{{X_1}}}\\
1 \le \dfrac{{{n_{{X_1}}}}}{{{p_{{X_1}}}}} \le 1,5 \Rightarrow 1 \le \dfrac{{18 - 2{p_{{X_1}}}}}{{{p_{{X_1}}}}} \le 1,5\\
\Rightarrow 5,14 \le {p_{{X_1}}} \le 6 \Rightarrow {p_{{X_1}}} = 6 \Rightarrow {n_{{X_1}}} = 18 - 2 \times 6 = 6\\
{A_{{X_1}}} = {p_{{X_1}}} + {n_{{X_1}}} = 12\\
{p_{{X_2}}} = {e_{{X_2}}} = {p_{{X_1}}} = 6\\
\Rightarrow {n_{{X_2}}} = 20 - 6 - 6 = 8\\
{A_{{X_2}}} = {p_{{X_2}}} + {n_{{X_2}}} = 6 + 8 = 14\\
\% {X_1} = \% {X_2} = 50\% \\
\overline {{M_X}} = \frac{{12 \times 50 + 14 \times 50}}{{100}} = 13
\end{array}\)
