Josie is running her first cross country meet. The race is a distance of 5 km and she has set a goal to finish the race in 21 minutes. She must run at a speed of to meet this goal.

3.97 m/s

Explanation:

Speed is defined as the distance covered per unit time. Therefore, s=d:t=d/t

Where d is distance and t is time

Given distance of 5 km and time of 21 minutes the speed would be given by dividing 5 km by 21 min. However, speed is expressed as km/h or m/s or miles per hour etc. So we nees to get our speed in one of these standard units.

Going for m/s

Conversion

1 km has 1000m hence

5 km=5*1000=5000m

1 min has 60 seconds hence

21 min=21*60=1260 s

Speed=5000m:1260s=3.9682539682538 m/s

Rounded off, s=3.97 m/s