4- The coordinates of four precipitation gauging stations are A = (3,4), B = (9,4), C =(3,12), and D = (9,12). The observed precipitation amounts at these gauges are PA

= 25 mm, PB = 33 mm, PC 20 mm, PD 29 mm, respectively. These stations are located in a rectangular basin whose boundaries are defined by the following coordinates (0,0), (14,0), (14,13), (0,13). If the units of the coordinate points given above are km, compute the mean areal precipitation over this basin using: a. The Thiessen polygons method b. The arithmetic average method c. Compute the total volume of water produced by the recorded rainfall.