[填空题]
A student measures a bqm9.n lw.-om(vpt h9 leri2xd bmts,0) ngth five times. All of the measurements lie between $18.8 \mathrm{~cm}$ and $19.2 \mathrm{~cm}$. What should the student quote as the absolute uncertainty in the length? The absolute uncertainty is $cm$ (please only input numerical value without units and without the $\pm$ symbol.)