Answer:
1.7 miles.
Step-by-step explanation:
We have been given that Mark runs back and forth on a football field for a total of 3000 yards.
Since we know that 1 mile equals to 1760 yards. To find the number of miles Mark ran we will divide 3000 yards by number of yards in one mile (1760).

After cancelling out yards from numerator and denominator we will get,

Therefore, Mark ran 1.7 miles on the football field.