1) 
    x <-c(2.5, 2, 5, 1, 11, -0.1, 10, 9)
    y <- seq(10, 6.5, by = -0.5)
    z <- 1:8

a) minmax_x <- range(x)
     minmax_y <- range(y)
     minmax_z <- range(z)

b) sum_x <- sum(x)
     sum_y <- sum(y)
     sum_z <- sum(z)
c)  x + y

d)  x - y - z

e)  prod_y <- prod(y)

f)  w <- c(x, y, z)
     campione <-  sample(w, floor(length(w)*0.3))

2a) 
     x <- c(2, 2, 0, 0, 5,
            8, 3, 4, 1, 0, 
            0, 7, 1, 7, 1,
            5, 4, 0, 4, 0);
	codici <- paste("Lav", 0:19, sep="");
	names(x) <- codici

b)  	x["Lav6"]

c)   zero.malattia <- sum(x==0)
     codici[x==0]  
     
d)  x[setdiff(codici, c("Lav2", "Lav11"))]