No. TahunCurahHujan ( Xi - Xa ) ( Xi - Xa )²

Xi (mm) (mm) (mm)

1 2003 868.20 -493,2 243246,24

2 2004 1387.40 26 676

3 2005 1198.50 -162,9 26536,41

4 2006 1566.10 204,7 41902,09

5 2007 1098.30 -263,1 69221,61

6 2008 1405.10 43,7 1909,69

7 2009 1228.50 -132,9 17662,41

8 2010 1499.80 138,4 19154,56

9 2011 1681,0 319,6 102144,2

10 2012 1681,1 319,7 12208,09

n 10 ƩXi = 13614,0 Ʃ = 624661,26

Xa = Ʃ Xi

n =

13614,010

= 1361,4 mm/thn

Xt = Xa + Yt−Yn

Sn√Ʃ ¿¿¿

= 1361,4 + 2,2502−0,49520,9456 √ 624661,26

10−1 = 1850,357

mm/thn

= 154,196 mm/bulanKeterangan :

Xt = Curah hujan rata-rata

Xa= Harga pengamatan rata-rata

Xi = Harga pengamatan tertentu

Yn= Reduced Mean

Yt= Reduced Variate

Sn = Reduced Standard Deviation

Lampiran P.2 Perhitungan Curah Hujan Rata-rata