A hiker walked 12.8 miles from 9:00 a.m. to noon. He walked an additional 17.2 miles from 1:00 p.m. to 6:00 p.m. What is his average rate for the entire walk, in miles per hour?

The average speed is the distance divided by the time.

Total distance:
12.8 miles + 17.2 miles = 30 miles

Total time:
noon - 9:00 a.m. = 3 hours
6:00 p.m. - 1:00 p.m. = 5 hours
Total time = 3 hours + 5 hours = 8 hours

average speed = 30 miles / 8 hours = 3.75 miles per hour