set.seed(12345)

n<-10000;

poi3<-rpois(n, 3)
poi5<-rpois(n, 5)
poi10<-rpois(n, 10)
poi15<-rpois(n, 15)

par(mfrow=c(2,2))

hist(poi3, breaks=100, xlab="mu=3")
hist(poi5, breaks=100, xlab="mu=5")
hist(poi10, breaks=100, xlab="mu=10")
hist(poi15, breaks=100, xlab="mu=15")