Does Halving Molecules Double RMS Speed?

[sArGe99]

Does the rms speed of a gas change when the no of molecules are lowered, isothermally?
I know that at same temp, avg kinetic energy remains the same.
m₁ (v₁)² = m₂ (v₂)²

If m2 = m1/2, v₂² = 2 v₁²
Is this correct?

 

[kuruman]

The number of molecules is N as in pV = NkT. The symbol m stands for the mass of a molecule, not the number of molecules.