Correct. Given $\displaystyle{{s}}^{{2}}={50}\usepackage{cmbright}\Huge\$ , you know $\displaystyle\sqrt{{{{s}}^{{2}}}}=\sqrt{{{50}}}={5}\sqrt{{{2}}}\usepackage{cmbright}\Huge\$ , and therefore $\displaystyle{s}={5}\sqrt{{{2}}}\usepackage{cmbright}\Huge\$ .