Answer:
4.2 miles per/hour
Explanation:
we know
speed total distance covered/ total time taken to cover that distance.
Time from 9:00 Am to 11:30 Am is 2 hours 30 minutes
time = 2 1/2 hours = 5/2 hours
for distance\
By 11:30 AM, he was 13 miles from the start.
so he covered a total distance of 12 miles
At 9:00 AM, a person running a race was 2 1/2 miles from the start
until 9 am he had already ran 2 1/2 miles = 5/2 miles
since we have to take distance travelled from 9 to 11 :30 Am
we need to subtract distance travel until 9 am from total distance traveled until 11:30 pm
Distance travlled from 9:11:30 am = distance traveled from start till 11:30AM - distance traveled from start till 9 AM
Distance traveled from 9:11:30 am = 13 - 5/2 = (26-5)/2 = 21/2
Thus, speed = 21/2 / 5/2 = 21/5 = 4 1/5 miles/hour = 4.2 miles/hour
Thus, he was running with 4.2 miles per/hour.