SEMI AVERAGE

TAHUN ( n )
PENJUALAN ( y )
X XY X²
1996 17500 -9 -157500 81
1997 21500 -7 -150500 49
1998 24000 -5 -120000 25
1999 27500 -3 -82500 9
2000 30000 -1 -30000 1
2001 32000 1 32000 1
2002 35000 3 105000 9
2003 37500 5 187500 25
2004 39000 7 273000 49
2005 41200 9 370800 81
305200 Σ=0 427800 330


TAHUN PENJUALAN X SEMI TOTAL SEMI AVERAGE
1996 17500 0
1997 21500 1
1998 24000 2
---->
120500 120500 = 24100 (Y1)
5

1999 27500 3
2000 30000 4
2001 32000 5
2002 35000 6
----->
184700 184700 = 36940 ( Y2)
5
2003 37500 7
2004 39000 8
2005 41200 9


Y1 = a + bx1
Y2 = a + bx2

JADI,,

24.100 = a + 2b
36.940 = a + 7b
b = 2568
a = 18964


Y06 = a + bx
= 18964 + 2568 ( 10 )
= 44.644