We know that there are 3600 seconds in an hour. So
divide 21.4 by 3600 to get a proportion of 21.4 seconds
to 1 hour, which is 0.00594¯6:1.
Knowing that 1000 meters are equivalent to a
kilometer, divide
200 m by 1000, which gives you 0.2 km.
So, the sprinter is running 0.2 km per every 0.00594¯6 hours.
To get the answer in kilometers, multiply both sides by (0.2 and 0.00594¯6)
to get ≈ 33.8 km/hr.
