$\begin{array}{l}
{\sigma _{\overline {{x_2}} }} = \frac{2}{3}{\sigma _{\overline {{x_1}} }}\,\,\,\,\, \Rightarrow \frac{\sigma }{{\sqrt {{n_2}} }} = \frac{2}{3} \times \frac{\sigma }{{\sqrt {{n_1}} }}\,\,\,\\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \Rightarrow \frac{1}{{\sqrt {{n_2}} }} = \frac{2}{3} \times \frac{1}{{\sqrt {{n_1}} }}\,\\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \Rightarrow 3\sqrt {{n_1}} = 2\sqrt {{n_2}} \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \Rightarrow 9{n_1} = 4{n_2}\\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \Rightarrow \frac{{{n_2}}}{{{n_1}}} = \frac{9}{4} = 2/25
\end{array}$