\frametitle {\LARGE Exercise 4 }
  {
  The file \\
{\tt \footnotesize
  http://www2.imm.dtu.dk/courses/02443/projects/data/Eurostoxx50.txt}}
contains stock prices of ABN Amro Holding, Aegon, Ahold Kon. and Air
Liquide.
 \begin{enumerate}
      \item Load them as a data.frame
 \item Plot the variation of the
prices as a function of time on the same plotting window with
different colors and line types.
 \item Add axes labels and title.
 \item Add a legend. [See {\tt ? legend}].
  \end{enumerate}