The following data give the number of driving citations received during the last three years by 12 drivers. $\begin{array}{llllllllllll}4 & 8 & 0 & 3 & 11 & 7 & 4 & 14 & 8 & 13 & 7 & 9\end{array}$
a. Find the mean, median, and mode for these data.
b. Calculate the range, variance, and standard deviation.
c. Are the values of the summary measures in parts a and $\mathrm{b}$ population parameters or sample statistics?