Jawabanmu

2014-09-06T14:07:49+07:00
Rata-rata = 18+21+20+18+23 / 5 = 20
varians = (18-20)^2 + (21-20)^2 + (20-20)^2 + (18-20)^2 + (23-20)^2 / 5
= 4+1+0+4+9 / 5 = 18/9 = 2
standar variasi = √2