From the given stem-and-leaf plot, we extract the data points as follows:
\[
\text{Stem} \, 0: \, 2 \quad \Rightarrow \quad 2
\]
\[
\text{Stem} \, 1: \, 6, 8 \quad \Rightarrow \quad 16, 18
\]
\[
\text{Stem} \, 2: \, 4, 4, 8, 9 \quad \Rightarrow \quad 24, 24, 28, 29
\]
\[
\text{Stem} \, 3: \, 2 \quad \Rightarrow \quad 32
\]
Thus, the complete dataset is:
\[
\{2, 16, 18, 24, 24, 28, 29, 32\}
\]
The mean \( \mu \) is calculated using the formula:
\[
\mu = \frac{\sum_{i=1}^N x_i}{N}
\]
Where \( N \) is the number of data points. Here, \( N = 8 \) and the sum of the data points is \( 173 \):
\[
\mu = \frac{173}{8} = 21.6
\]
To find the median, we first determine the rank using the formula:
\[
\text{Rank} = Q \times (N + 1) = 0.5 \times (8 + 1) = 4.5
\]
Since the rank is not an integer, we take the average of the values at ranks 4 and 5:
\[
Q = \frac{X_{\text{lower}} + X_{\text{upper}}}{2} = \frac{24 + 24}{2} = 24.0
\]
The results are as follows:
Mean: \( \mu = 21.6 \)
Median: \( Q = 24.0 \)
Thus, the final answers are:
\[
\boxed{\text{Mean: } 21.6}
\]
\[
\boxed{\text{Median: } 24.0}
\]