A population inversion for two energy levels is often described by assigning a negative Kelvin temperature to the system. What negative temperature would describe a system if the population of the upper energy level exceeds that of the lower level by $\backslash (9\mathrm{.}0\backslash \%\backslash )$ and the energy difference between the two levels is $2\mathrm{.}76$ eV $?$