Final answer:
The marathon runner takes 2.76 hours to run a 26.22-mile marathon.
Step-by-step explanation:
To find out how long it takes for the marathon runner to run a 26.22-mile marathon, we can use the formula: time = distance / speed. In this case, the distance is 26.22 miles and the average speed is 9.5 mi/h. So, the time it takes is 26.22 miles / 9.5 mi/h = 2.76 hours.
Therefore, the correct answer is a) 2.76 hours