Deep in space there is an average particle density = 0 . 9 9 cm -3

 Deep in space there is an average particle density $\mathrm{\rho }=0\mathrm{.}99$ cm$^-3$³ and an extremely low pressure of P$0=4\mathrm{.}9$ x $10$^-
1-17 N$/$m$\mathrm{²}.$ What is the average temperature of $($mostly$)$ empty space? Give your answer in K$.$