Within R there are some sample data.frames to use in examples.

  1. Display the variables and variable classes for the data.frame mtcars.
  2. How many cars are there for each possible choice of number of cylinders.
  3. Create a new data.frame that adds a column for the new computed variable mpg/cyl.
  4. What is the mean horsepower (hp) for the cars with 4 gears?