To find the median of the given data set, let's first extract the values from the stem-and-leaf plot and arrange them in ascending order.

The key provided is 4|3 = 43 years old, meaning that each number to the left of the vertical line represents the tens digit, and the numbers on the right are the ones digit.

Data extraction from the stem-and-leaf plot:

• 1 | 9 → 19
• 2 | 5 6 6 → 25, 26, 26
• 3 | 0 3 → 30, 33
• 4 | 2 4 4 5 6 → 42, 44, 44, 45, 46
• 5 | 6 7 → 56, 57
• 6 | 8 → 68
• 7 | 3 → 73

Now, let's list the data in order:

19, 25, 26, 26, 30, 33, 42, 44, 44, 45, 46, 56, 57, 68, 73

There are 15 data points in total. The median is the middle value, which is the 8th value in the sorted list:

Median = 44

The median of the data set is 44.

Would you like further clarification or more details on how the median is calculated?

Here are some related questions:

1. What is the mode of this data set?
2. What is the range of this data set?
3. How do you calculate the mean of this data set?
4. What is the significance of using a stem-and-leaf plot?
5. Can you determine the interquartile range (IQR) from this data set?

Tip: The median is a measure of central tendency that helps reduce the effect of outliers, as it focuses on the middle of the dataset.