x<-c(19,17,15,10,24,14,23,15,16,21,10,21,12,14,21,22,24,15,18,14,21,20,15,11,22)
length(x)
mean(x)
min(x)
median(x)
lk<-c(9.5,12.5,15.5,18.5,21.5,24.5)
hist(x, breaks = lk)