Answer:
The runner attain to 18 miles per hour speed.
Step-by-step explanation:
First we calculate the velocity in meters per second:
[tex]v=e/t[/tex]
Where v is velocity, e is distance traveled, and t time taken to travel the distance e.
[tex]v=400m/50sec=8m/s[/tex]
So, the speed is 8m/s and now we need to convet to miles per hour.
[tex]\frac{8m/s}{1609m}*\frac{1mile\int\limits^a_b {x} \, dx }{1hour}*3600s=17,89[/tex]
Rounded: 18 miles per hour