9) The area shown in Fig. 1 is composed of a square plus an equilateral triangular plot of side 10 km. The annual precipitation at the rain gauge stations at the four corners and the center of the square plot and apex of the triangular plot are indicated in the below figure. Find the mean precipitation over the area by Thiessen polygon method and compare with the arithmetic mean. F (60cm) 10km 10km A (46cm) D (80cm) Fig.1 10km E (70cm) B (65cm) 10km C (76cm) Page 8