Please be clear with your solution.
Extracted text: 4. The monthly rainfall data and the respective altitudes for 10 rain gauges in a sub-basin of Mati River are shown in Table below. Calculate the average surface rainfall using the methods of arithmetic mean, Thiessen and Isohyetal curves. Moreover, an adjustment of the average surface rainfall calculated by the Thiessen method with respect to the average elevation of the basin should be made. The area of the basin is equal to 2940 km², and N the average elevation of the basin is equal to 532 m. Rainfall Rainfall Altitude (m) Station Area (sq. km.) Interval Area (sq.km) Station (mm) (mm) 65-70 8 1 226 74 1 316 74 70-75 444 2 220 73 2 153 73 75-80 295 581 92 3 216 92 80-85 405 4 842 101 4 212 101 85-90 729 5 500 83 5 238 83 90-95 506 596 87 582 87 95-100 327 7 1050 110 7 194 110 100-105 149 8 860 103 8 177 103 105-110 55 9 116 82 9 550 82 110-115 22 10 87 70 10 302 70 2940 Total 2940