# durtel
# fai via via un CLIC sul grafico; quando vuoi finire premi ESC
par( mai = c(0.5,0.5,0.2,0.2) )
while(1 < 2) {
m <- 48.7; s <- 20; x <- 0; y <- 0
j <- 1; while(j < 101) {
  for (i in 1:20) x[i] <- runif(1)
  k <- s*sqrt(0.6)*(sum(x)-10)+m
  if(k > 0) {y[j] <- k; j <- j+1} }
hist(y,probability=TRUE,ylim=c(0,0.03),cex.axis=0.88,col="yellow")
abline(h=seq(5,30,5)/1000,lty=3)
text(25,0.029,"media"); text(25,0.027,round(mean(y)*100)/100)
locator(1)
}