Answer: Her average speed would be 8.89 miles per hour.
Explanation:
Since we have given that
Time taken to run from mile marker 1 to mile marker 2 = 6 minutes
Time taken to run from mile marker 2 to mile marker 4 = 21 minutes
So, Number of miles from 1 to 4 = 4 miles
total time taken = 6+21 = 27 minutes
So, Average speed would be
![(4)/(27)* 60\\\\=(240)/(27)\\\\=8.89\ mph](https://img.qammunity.org/2019/formulas/mathematics/middle-school/56emduio5zmnf1jmpniq4a4d5iska05o10.png)
Hence, her average speed would be 8.89 miles per hour.