Which is INCORRECT regarding the command: T <- 40; rnorm( T, 1, 4) ?

What is the result of command: z <- c(1:3,NA); ind <- is.na(z); z ?

How does a matrix differ from a data frame?

What value does this statement return? unclass(as.Date("1971-01-01"))

What do you use to take an object such as a data frame out of the workspace?

The variable height is a numeric vector in the code below. Which statement returns the value 35?

What is the output of dim(matrix(1:10, ncol=2))?

What is the output of the following R function? yyy <- c(1, 3, NA); fff <- function(xxx) {mean(xxx)}; fff(yyy)

What does the following R code output? Y <- c(1,2,3); X <- rep(c(1,length(Y)), times=2); X

What is the output for the command: is.na(0/0)?

What R function can be used to tabulate values of categorical variable Y (columns) by categorical variable X (rows)?