Fred rafts down a river that has a rectangular cross section. In the first part of the river, which is $8$ m across, he is traveling at a rate of $\backslash (4\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}\backslash )$ and in the second part of the river he is traveling at a rate of $\backslash (1\mathrm{.}2\backslash$mathrm$\{$~m$\}/\backslash$mathrm$\{$s$\}\backslash ).$ If the river has a constant depth, what is the width of the river in the second part $($in m$)?$