Three closed vessels A, B and C are at the same temperature T and contain gasses which obey the Maxwellian distribution of velocities. Vessel A contain only `O_2 and N_2`. If the average speed of the `O_2` molecules in vessel A is `v_1` that of the `N_2` molecules in vessel B us `v_2,` the average speed of the `O_2` molecules in vessel C is