A watertight rectangular box, $1\mathrm{.}2$ m long and $0\mathrm{.}75$ m wide, floats with its sides and ends vertical in water of density $1000k\frac{g}{m^3}.$ If the depth of the box in the water is $280$ mm $,$ what is its weight? $[2\mathrm{.}47$ kN $]$