Suppose a runner completes a 10k (10.0 km) road race in 41 minutes and 25 seconds. what is the runner's average speed in miles per hour?

Answer;

9 miles per hour.

Solution;

Convert 41 minutes to seconds and add 25 seconds to that, then divide by 60 to convert to hours.

41 min = 2460 seconds ( + 25 seconds) = 2485 / 60 = 41.417 minutes (0.6903 hours).

Speed = 10 km/0.6903 hr = 14.4869 km/hr

But 1 mile = 1.60934 km

Thus; 14.4869 kilometers = 9.0017 miles.

So the runner's average speed is roughly 9 miles per hour.