lambda <- 2
 numsim <- 100
 mean5 <- rep(0,numsim)
 mean25 <- mean5; mean100 <- mean5
 for (i in 1:numsim) {
    mean5[i] <- mean(rexp(5,lambda))
    mean25[i] <- mean(rexp(25,lambda))
    mean100[i] <- mean(rexp(100,lambda))
    }
 boxplot(mean5,mean25,mean100,names=c("n=5","n=25","n=100"))
 title("Distribution of means of Exponentials")