Jerome is keeping track of how many books he and his friends have read during the first $100$ days of school. Make a stem-and-leaf plot of how many books each person has read to help Jerome present the data to his teacher. The numbers of books are: $12$, $17$, $10$, $24$, $18$, $31$, $17$, $21$, $20$, $14$, $30$, $9$, $25$. .

1. Make a stem-and-leaf plot of the data.

   Answer (a):

   $\begin{array}{r|l} \quad \text{Stem: 4} & \text{Leaf: 1 means 41} \quad \\ \hline 0 & 9 \\ 1 & 0, 2, 4, 7, 7, 8\\ 2 & 0, 1, 4, 5\\ 3 & 0, 1 \end{array}$

2. Jerome wants to present the data with a plot that makes it possible to calculate the mean, median, and mode. Can he do this with a stem-and-leaf plot? He is not asking you to calculate them, but he wants you to tell him if it is possible and why.

   Hint (b):

   What do you need to be able to calculate the mean, median and mode?

   Answer (b):

   Yes, the stem-and-leaf plot shows all of the data points.

3. Use the stem-and-leaf plot to describe how the data is spread. That is, is it spread out? Or is it concentrated mostly in a narrow range?

   Hint (c):

   Do some numbers seem to show up in a certain spot more than others?