Answer:
[tex]100\ \text{ft/mi}[/tex]
Step-by-step explanation:
Elevation of the head of the stream is 2,200 feet above sea level
Elevation of the mouth of the stream is 1,000 feet
Rise = [tex]2200-1000=1200\ \text{ft}[/tex]
Distance between the two points = [tex]63360\ \text{ft}=\dfrac{63360}{5280}=12\ \text{mi}[/tex] = Run
Gradient is given by
[tex]\dfrac{\text{Rise}}{\text{Run}}=\dfrac{1200}{12}\\ =100\ \text{ft/mi}[/tex]
The gradient of the slope the stream is flowing over is [tex]100\ \text{ft/mi}[/tex].