\begin{gather*} v = \frac{25}{6} - \left ( \frac{3}{2} \right )^2 = \frac{43}{12} \approx 3.58 ,\\ s^2 = \frac{6}{5} \times v = \frac{43}{10} = 4.3,\\ \text{and so } s = \sqrt{4.3} \approx 2.07 \end{gather*}