library(actuar)
data(dental)
emm(dental,order=1:2)
m1<-353.3399 
m2<-357680.2249
u<-m2/m1^2
1/(u-1)
m1/(u-1)
a<-1/(u/2-1)+2
a
m1*(a-1)

data(gdental)
x<-gdental
sum(gdental[,2])
hist(x)
Fnt<-ogive(x)
knots(Fnt)
Fnt(knots(Fnt))
plot(Fnt)

emm(gdental,order=1:2)