moneta <- c("TESTA", "CROCE")
urna <- c(rep("ROSSA",6),rep("NERA",4))
nlanci <- 100000
x <- rep(NA,nlanci)
for (i in 1:nlanci)
{
    out <- sample(moneta,size=1)
    if (out=="TESTA") ris <- sample(urna,size=2,replace=TRUE)
    if (out=="CROCE") ris <- sample(urna,size=3,replace=FALSE)
    x[i] <- sum(ris=="ROSSA")
}
frequenze(x)
mean(x)
var(x)