Da marathon runner runs at a average speed of 5.33 meters per second for the first
73600 seconds and then at a speed of 5.00 meters per second for the next 4200
seconds. what is the average speed of the marathon runner in meters per second?
f
5.1 m/s
g
2.6 m/s
h
0.4 m/s
j 1.06 m/s

The average speed of the marathon runner is 5.15 meters per second

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