Answer:
The average speed of the marathon runner is 5.15 meters per second
Step-by-step explanation:
Lets revise the meaning of average speed
The average speed of an object is the total distance traveled by
the object divided by the time taken to cover that distance
A marathon runner runs at a average speed of 5.33 meters per second
for the first 3600 seconds
⇒ His speed = 5.33 m/s
⇒ For time = 3600 seconds
Then he runs at a speed of 5.00 meters per second for the next
4200 seconds
⇒ His speed is 5 m/s
⇒ For time 4200 seconds
Average speed = total distance ÷ total time
Lets find the total distance
Distance = speed × time
⇒ The 1st distance = 5.33 × 3600 = 19188 meters
⇒ The 2nd distance = 5 × 4200 = 21000 meters
⇒ Total distance = 19188 + 21000 = 40188 meters
Lets find the total time
⇒ Total time = 3600 + 4200 = 7800 seconds
⇒ Average speed = 40188 ÷ 7800 = 5.15 m/s
The average speed of the marathon runner is 5.15 meters per second