Two bodies of mass 1 kg and 3 kg have position vectors $\hat{\mathrm{i}}+2 \hat{\mathrm{j}}+\hat{\mathrm{k}}$ and $-3 \hat{\mathrm{i}}-2 \hat{\mathrm{j}}+\hat{\mathrm{k}}$ respectively. The magnitude of position vector of centre of mass of this system will be similar to the magnitude of vector :