$4)$ An object hangs from a spring balance. The balance registers $40\mathrm{.}0$ N in air, $30\mathrm{.}0$ N when the object is immersed in water $($density $1000$ kg$/$m$3),$ and $32\mathrm{.}0$ N when the object is immersed in another liquid of unknown density. What is the density $($kg$/$m$3)$ of that other liquid?