For the $6 \mathrm{~m}$ long horizontal cantilever beam $\mathrm{PQR}$ shown in the figure, $\mathrm{Q}$ is the midpoint. Segment $\mathrm{PQ}$ of the beam has flexural rigidity $\mathrm{EI}=2 \times 10^{5} \mathrm{kN. \textrm {m } ^ { 2 }}$ whereas the segment $Q R$ has infinite flexural rigidity. Segment $Q R$ is subjected to uniformly distributed, vertically downward load of $5 \mathrm{kN} / \mathrm{m}$.
The magnitude of the vertical displacement (in $\mathrm{mm}$ ) at point $\mathrm{Q}$ is $\_\_\_\_\_\_\_$ (rounded off to $3$ decimal places).