A recent attempt to circumnavigate the world in a balloon used a helium filled balloon whose volume was $7240$ m$\backslash$deg and surface area was $1800$ m$?.$ The skin of this balloon is $2$ mm thick and is made of a material whose helium diffusion coefficient is $1$x$10\backslash$deg m $/.$ The molar concentration of the helium at the inner surface of the balloon skin is $0\mathrm{.}2$ kmol$/$m$\backslash$deg and the molar concentration at the outer surface is extremely small. Calculate the mass rate $($Kg$/$hr$)$ at which helium is lost from this balloon.