Asprinter set a high school record in track and field, running 200.0 m in 21.4 s . what is the average speed of the sprinter in kilometers per hour?

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.

d.7.5cm is your answer