In a double$-$slit interference experiment, the wavelength is $=4\mathrm{.}7{10}^{-7}m,$ the slit separation is $d=4\mathrm{.}2{10}^{-3}m.$ Only consider the bright fringes on one side of the central bright fringe. If the linear distance between the $2$ nd order bright fringe and the $6$ th order bright fringe on the screen is $6\mathrm{.}2{10}^{-3}m,$ what is the distance L$($unit in m$)?$