Answer:
285.7 miles per hour
Explanation:
You would set up 2 equations that are equal to each other, and solve for the missing quantity. IN this case we are missing the distance for the average, so we'll call that d. This is how you set it up;
d / t = d / t
1000miles / 5.5hrs = d / 1hr
Solve for time, and you get 285.7 Miles per hour