A catchment may be idealized as a circle of radius 30 km. There are five rain gauges, one at the center of the catchment and four on the boundary (equi-spaced), as shown in the figure (not to scale). The annual rainfall recorded at these gauges in a particular year are given below.
\includegraphics[width=1.0\linewidth]{image222.png}
Using the Thiessen polygon method, what is the average rainfall (in mm, rounded
off to two decimal places) over the catchment in that year? \underline{\hspace{1cm}\-\underline{\hspace{0cm}}}
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