### ex1.1 ###### 

a <- 1:5
ma <- mean(a, na.rm = TRUE)
sda <- sd(a, na.rm = TRUE)
a - ma
(a - ma)/sda

### ex1.2 ######

vec <- seq(4, 100, 7)
select <- vec%%5 == 0
vec[select]

### Assignment 1

set.seed(123321)
item1 <- rnorm(100, 50, 10)
c(mean(item1), sd(item1))

item3 <- rnorm(10000, 50, 10)
c(mean(item3), sd(item3))