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4-65.

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.

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

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.

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

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?

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

Make a stem-and-leaf plot using the eTool below.
Click the link at right for the full version of the eTool: MC2 4-65 HW eTool