From the kinetic energy formula it can be shown that
where v is in m/s, T is in kelvin, and m is the mass of one molecule of gas in kg. The most probable (or mode) speed  is 81.6% of the root-mean-square speed , and the mean (arithmetic mean, or average) speed  is 92.1% of the rms speed (isotropic distribution of speeds).
See: 
* Average, 
* Root-mean-square speed
* Arithmetic mean
* Mean
* Mode (statistics)