To find the mean of the high temperatures, we use the formula:
\[
\mu = \frac{\sum_{i=1}^N x_i}{N}
\]
where \( N \) is the number of data points and \( x_i \) are the individual temperature values. For the high temperatures:
\[
\mu = \frac{18 + 24 + 30 + 44 + 55}{5} = \frac{171}{5} = 34.2
\]
Thus, the mean of the high temperatures is \( 34.2 \, ^\circ \text{F} \).
To find the median, we first sort the high temperatures:
\[
\text{Sorted data: } [18, 24, 30, 44, 55]
\]
Since there are 5 data points (an odd number), the median is the value at position \( \frac{N + 1}{2} = \frac{5 + 1}{2} = 3 \). Therefore, the median is:
\[
\text{Median} = 30 \, ^\circ \text{F}
\]
Using the same mean formula for the low temperatures:
\[
\mu = \frac{\sum_{i=1}^N x_i}{N}
\]
For the low temperatures:
\[
\mu = \frac{9 + 14 + 19 + 31 + 44}{5} = \frac{117}{5} = 23.4
\]
Thus, the mean of the low temperatures is \( 23.4 \, ^\circ \text{F} \).
We sort the low temperatures:
\[
\text{Sorted data: } [9, 14, 19, 31, 44]
\]
Again, with 5 data points, the median is at position \( \frac{N + 1}{2} = 3 \). Therefore, the median is:
\[
\text{Median} = 19 \, ^\circ \text{F}
\]
The results are as follows:
- The mean of the high temperatures is \( 34.2 \, ^\circ \text{F} \).
- The median of the high temperatures is \( 30 \, ^\circ \text{F} \).
- The mean of the low temperatures is \( 23.4 \, ^\circ \text{F} \).
- The median of the low temperatures is \( 19 \, ^\circ \text{F} \).
Thus, the final answers are:
\[
\boxed{34.2 \, ^\circ \text{F}, \, 30 \, ^\circ \text{F}, \, 23.4 \, ^\circ \text{F}, \, 19 \, ^\circ \text{F}}
\]