Answer:
From mile marker 1 to mile marker 4 26 minutes
The average speed was 0,115 miles/minute
From mile marker 9 to finish the race average speed was 0,105 miles/minute
Step-by-step explanation:
Mark took 6 minutes from marker 1 to marker 2 ( 1 mile in 6 minutes)
and 20 minutes from marker 2 to marker 4 ( 2 miles in 20 minutes )
Then Mark took 26 minutes to get to marker 4 from marker 1 ( 3 miles)
then average speed is 3 / 26 = 0,115 miles/minute
71 minutes after starting the race Mark passed marker 9
Average speed 9 / 71 = 0,126 miles/minute
Mark complete the race in 110 minutes
Then Mark run 4,1 miles ( 13,1 - 9 = 4.1 ) from marker 9 to the end in 110 - 71 = 39 minutes at the average speed of 4,1 /39 miles /minute
4,1 / 39 = 0,105 miles/minute
