Simpan=read.csv("C:/Users/Asus/Downloads/Statistika milla/TugasVarians7.2.csv", sep=";")
Simpan
##    Nilai Kelas
## 1     30     1
## 2     40     1
## 3     50     1
## 4     60     1
## 5     70     1
## 6     80     1
## 7     90     1
## 8     10     2
## 9     20     2
## 10    30     2
## 11    40     2
## 12    50     2
## 13    60     2
## 14    70     2
library(doBy)
summaryBy(Nilai ~ Kelas, data = Simpan, FUN = function(x)
{ c(ratarata = mean(x), varians = var(x), jumlah=sum(x) ) } )
##   Kelas Nilai.ratarata Nilai.varians Nilai.jumlah
## 1     1             60      466.6667          420
## 2     2             40      466.6667          280