Trigonometric levelling was carried out from two stations $\mathrm{P}$ and $\mathrm{Q}$ to find the reduced level ($\text{R. L.}$) of the top of hillock, as shown in the table. The distance between Stations $\mathrm{P}$ and $\mathrm{Q}$ is $55 \mathrm{~m}$. Assume Stations $\mathrm{P}$ and $\mathrm{Q}$, and the hillock are in the same vertical plane. The $\text{R. L.}$ of the top of the hillock $\text{(in m)}$ is ____________ (round off to three decimal places).
$$\begin{array}{|l|l|l|l|}
\hline \textbf{Station} & \begin{array}{c}\textbf { Vertical angle of } \\
\textbf { the top of hillock }\end{array} & \begin{array}{c}\textbf { Staff reading on } \\
\textbf { benchmark }\end{array} & \textbf {R. L. of benchmark} \\
\hline \text{P} & 18^{\circ} 45^{\prime} & 2.340 \mathrm{~m} & 100.000 \mathrm{~m} \\
\mathrm{Q} & 12^{\circ} 45^{\prime} & 1.660 \mathrm{~m} & \\
\hline
\end{array}$$