Final answer:
To find by how many mph the median speed fell, compare the median speed before and after the bumps were built. Subtract the median speed after the bumps were built from the median speed before the bumps were built to find the difference.
Step-by-step explanation:
To find by how many mph the median speed fell, we need to compare the median speed before and after the bumps were built. First, let's find the median speed before the bumps were built.
The stem-and-leaf diagram shows that there are 15 data points before the bumps were built, so the median would be the 8th value in the sorted list. Since the speed values are already presented in increasing order in the stem-and-leaf diagram, we can directly read off the 8th value, which is 44 mph.
Next, let's find the median speed after the bumps were built. Again, the stem-and-leaf diagram shows that there are 15 data points after the bumps were built, so the median would be the 8th value in the sorted list. By reading off the 8th value, we can see that the median speed after the bumps were built is 40 mph.
To find by how many mph the median speed fell, we subtract the median speed after the bumps were built from the median speed before the bumps were built: 44 mph - 40 mph = 4 mph.