urna.1 <- c("VERDE","BLU")
urna.2 <- c("VERDE","ROSSA")

prove <- 100000
num <- 0; den <- 0

for (i in 1:prove)
{
    out.1 <- sample(urna.1,size=1,replace=FALSE)
    out.2 <- sample(urna.2,size=1,replace=FALSE)
    den <- den + 1
    if (out.1=="VERDE" & out.2=="VERDE") num <- num+1
}

cat(num,den,num/den,"\n")