Exercise $1(50$ points$)$: For the watershed map and rainfall data provided, calculate the mean precipitation over the watershed by the $3$ methods mentioned above.Hint: You will need to outline the watershed and rainfall stations on a $10$ x$10$ grid paper. The scale of the basin map is $1$:$50000,$ thus make the scale of the grid paper $1$:$50000.$ This means that every cm on the grid paper represents $50000$ cm $($or $0\mathrm{.}5$ km$)$ on the ground. Count the number of grid cells in your Thiessen polygons or in the area between isohyets. When you find out the number of cells, you can multiply that by the number of km$2$ that each cell represents. Since you are given a total watershed area of $32\mathrm{.}7$ km$2$ the totals for each polygon or isohyet should not be too far off that value.